


smetL a 




Class 
Book. 






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Copyright N?_ 



COPYRIGHT DEPOSIT. 



Ube IRural Uext>Book Series 

Edited by L. H. BAILEY 



MANURES AND FERTILIZERS 



Z\)t Ifcural Efxt=i3ooR Series 

Lyon and Fippin, Principles of Soil Man- 
agement. 
G. F, Warren, Elements of Agriculture. 

A. R. Mann, Beginnings in Agriculture. 
J. F. Duggar, Southern Field Crops. 

B. M. Duggar, Plant Physiology, with 
Special Reference to Plant Production. 

G. F. Warren, Farm Management. 

M. W. Harper, Animal Husbandry for 

Schools. 
E. G. Montgomery, The Corn Crops. 
H. J. Wheeler, Manures and Fertilizers. 



MANURES AND FERTILIZERS 



A TEXT-BOOK FOE COLLEGE STUDENTS AND A 

WORK OE REFERENCE FOR ALL INTERESTED 

IN THE SCIENTIFIC ASPECTS OF 

MODERN FARMING 



BY 



HOMER J. WHEELER, Ph.D., D.Sc. 

AGRICULTURAL CHEMICAL EXPERT OF THE AMERICAN AGRICULTURAL CHEMICAL 

COMPANY AND FORMERLY PROFESSOR OF AGRICULTURAL CHEMISTRY 

AND DIRECTOR OF THE AGRICULTURAL EXPERIMENT 

STATION OF THE RHODE ISLAND 

STATE COLLEGE 



Neto If ork 

THE MACMILLAN COMPANY 

1913 

All rights reserved 



; f> h 



S<b33 
AN 5 



Copyright, 1913, 
Bt THE MACMILLAN COMPANY, 



Set up and electrotyped. Published August, 1913. 



Norton 00 $rass 

J. 8. Cushing Co. — Berwick & Smith Co. 

Norwood, Mass., U.S.A. 



©CI.A354 09 7 



PREFACE 

The preparation of this volume was undertaken for the 
purpose of meeting a distinct lack in collegiate agricultural 
textbooks in the United States. It was hoped to prepare a 
book reasonably free from extended details, such as are 
found in certain of the larger foreign works, and likewise 
to avoid the rather superficial treatment of the subjects 
which has necessarily characterized many of the books 
which have been written for the purpose of meeting the 
earlier requirements of the American agricultural colleges, 
and the present demands of agricultural high schools. The 
intent has been to provide in a measure for the needs of the 
graduate student in agriculture ; also for the requirements 
of students in the agricultural colleges, teachers in agricul- 
tural schools, graduates of agricultural schools and colleges, 
agricultural institute lecturers, and the rapidly increasing 
number of intelligent men who are daily interesting them- 
selves in the scientific phases of modern farming. 

In connection with the treatment of some of the newer 
and more controversial phases of certain of the topics, au- 
thorities have been cited freely, in order that the reader may 
readily pursue the subjects further, if desired. These cita- 
tions have been introduced at the bottom of the respective 
pages, so as to permit of more convenient and ready ref- 
erence than would be possible if they were placed at the 
ends of chapters, or at the end of the volume. 

Certain points have been referred to repeatedly in dif- 



vi PREFACE 

ferent connections, in order that the reader may not have 
his train of thought interrupted by frequent enforced refer- 
ence to preceding pages or chapters. 

The subject of guano and of human excrement will per- 
haps be thought to have been treated too fully from the 
historical standpoint, yet the agricultural teacher is ex- 
pected to be conversant with such matters, and he can best 
familiarize himself with them when they are being con- 
sidered in their manurial relations. 

Unusual attention has been paid to the sea-weeds of the 
Atlantic coast for the reason that they are largely used 
directly as fertilizers by the farmers, whereas those of the 
Pacific coast, on account of their larger size, are now being 
more generally utilized in a commercial way. The consid- 
eration of sea-weeds is important, for notwithstanding that 
they interest directly only a relatively small section of the 
country, detailed information concerning them is not readily 
accessible to those students who need it. 

In the discussion of the dung of domestic animals, much 
attention is given to the bacteria and other organisms in- 
volved in its decomposition, for the reason that they greatly 
affect its value under the varying conditions of moisture and 
aeration. 

Not only have organic nitrogenous manures been carefully 
considered, but also the precautions necessary in determin- 
ing their relative availability, and the results of such deter- 
minations by different investigators. 

The subject of nitrates and of ammonium salts has been 
quite fully treated, especially from the standpoint of their 
cumulative and indirect effects. The new synthetic nitrog- 
enous fertilizers, calcium cyanamid and calcium nitrate, 
have also received attention. 

More than the customary amount of space has been devoted 
to the subject of lime and its use, and magnesia, soda, and 



PREFACE Vll 

manganese have been discussed more fully than in most of 
the previous works of its kind. 

Brief reference is made to the so-called catalytic fertilizers, 
and to the effect of carbon disulfid, tricresol, toluene, and 
other substances, certain of which are held to destroy soil 
amebe and ciliates, and hence to promote unusual bacterial 
development and ammonification. 

Care has been taken to discuss the reasons for many of 
the conflicting opinions on various subjects, in the belief 
that those entering upon agricultural research work should 
be taught to give such matters more careful consideration 
than is frequently the case. 

No apology is offered by the writer for the frequent refer- 
ence to certain lines of research work at the Rhode Island 
agricultural experiment station, for the reason that he can 
speak of these results in a more authoritative way than of 
work done elsewhere. Furthermore, the work has been, in 
some respects, of a pioneer character, and has not been 
duplicated. 

In certain of the chapters matter will be found which is 
of too theoretical a character to meet the needs of the casual 
reader, and he is requested to pass it over charitably, remem- 
bering that the prime object of this work is not to give rule- 
of-thumb directions, but rather to aid in inculcating such 
general principles as shall aid in making the student as 
independent as possible of them, and at the same time fur- 
nish a foundation upon which to base his future study of 
the various relations of fertilizers and manures to soils and 
crops. 

As a matter of convenience to the vast majority of read- 
ers, and because of the confusion incident to the use of the 
names of the elements in place of phosphoric acid, potash, 
soda, lime, and magnesia which are in common use through- 
out the civilized world, the old and well-established nomen- 



Vlii PREFACE 

clature has been retained, instead of following the lead of 
one or two American writers who have seen fit to depart 
from the universal custom. 

Acknowledgments are due to the agricultural experiment 
station of the Rhode Island State College for all of the 
illustrations which have been used; likewise to Brooks, 
Cameron, Deherain, Fritsch, Griffiths, Hall, Halligan, Hei- 
den, Hilgard, Johnson, King, Murray, Lohnis, A. Mayer, 
Miintz and Girard, Storer, Van Slyke, Voorhees, Vivian, and 
others, whose works have been freely consulted ; also to Mr. 
Wilcox, of Mystic, Conn., for details concerning the han- 
dling of menhaden, to L. H. Bailey and P. B. Hadley for 
helpful suggestions, and to my son, Carl 0. J. Wheeler, for 
aid in reading the proofs. A debt of acknowledgment is 
also recognized to Goessmann, Henneberg, Von Koenen, 
V. Meyer, Th. Pfeiffer, Tollens, and Stockbridge, whose 
work and teachings have been of fundamental assistance to 
the author, as well as a source of lasting inspiration. 

H. J. WHEELER. 
May 12, 1913. 



CONTENTS 

CHAPTER I 

PAGES 

Historical Introduction 1-9 

Chemistry throws new light on the subject of manuring 

— The views of Liebig — The early work of Lawes and 
Gilbert — Assimilation of atmospheric nitrogen by plants 

— Other facts established by Lawes and Gilbert — The 
utilization of nitrates and guano — Employment of ammo- 
nium salts — The manufacture and use of superphosphates 

— The German potash salts — The manufacture of basic 
slag meal — New processes for combining atmospheric nitro- 
gen — New catalytic and other fertilizers. 

CHAPTER II 

Night Soil 10-18 

Conservation of night soil now less necessary — Amount 
of urine produced per person — Chemical composition of 
human urine — The amount of solid excrement per indi- 
vidual — Former methods of disposal in Europe were bad 

— Orientals conserve human excrement carefully — The 
conservation of human excrement in Paris — Poudrette 
from human excrement — Treatment of excrement with 
burned lime — The " A. B. C. " and other methods of con- 
servation — The novel method of Sindermann — Repeated 
use encourages undue leaf growth. 

CHAPTER III 
The Dung of Farm Animals and its Preservation . . 19-34 
Influence of feed and age of animal on dung — Influence 
of litter on manure — Collecting and caring for dung — 
Horse manure — Cow manure — Sheep manure — Hog 

ix 



X CONTENTS 

PAGES 

manure — Hen and pigeon manure — Amounts of litter 
used as absorbents — Comparative absorbent power of 
litters for water and ammonia — The degree of conserva- 
tion effected by litters — Losses of manure lessened by 
packing and trampling — Soil a powerful absorbent of am- 
monia — Muntz and Girard's results on the absorption of 
ammonia — The action of gypsum as a preservative of 
manures — Keasons for using gypsum in excess — Gypsum 
safe to use — Gypsum compared with other chemical pre- 
servatives — Preservation by antiseptics. 

CHAPTER IV 

The Organisms and Fermentation of Dong . . . 35-54 
The number of microorganisms present in cow and 
horse manure — Significance of microorganisms in ma- 
nure — Microorganisms in litter — Urine, when voided, 
essentially free from microorganisms — The numbers 
of bacteria decrease gradually — The disadvantage of 
antiseptics — Types of microorganisms present in ma- 
nure — Aerobic forms — Spore-forming anaerobic forms 
— Actinomycetes — The yeasts — The molds and other 
organisms — Animal organisms destroy bacteria — The 
effect of heating and of antiseptics on manure — Destruc- 
tive changes in the non-nitrogenous matter of dung — 
Losses not confined to the cellulose — Most of the aerobic 
and anaerobic organisms in dung are active — Diastatic 
action — Decomposition of starch — Decomposition of pec- 
tin — Decomposition of cellulose — Decomposition of fats 
and waxes — Decomposition of urea — Decomposition of 
hippuric acid — Changes produced in uric acid — Ammon- 
ification of solid manure and litter — Terms used in dis- 
cussing the decomposition of dung — The nature and cause 
of the losses occurring in manure — Losses less by fer- 
mentation when moist and compact — Losses increased by 
bacteria from intestinal tract — Losses smaller in the later 
stages of decomposition — Fresh manure lacks immediate 
effectiveness — The great necessity of moisture in heaps of 
solid manure — The preservation of the liquid manure. 



CONTENTS Xi 

CHAPTER V 

PAGES 

The Practical Utilization of Manures .... 55-64 
Storage versus direct application of manures — Immedi- 
ate incorporation of manure with the soil — Losses occur- 
ring in heaps in the field and if broadcasted — The time to 
spread manure on fields — Certain vegetable substances aid 
denitrification in manures — Losses by denitrification less 
serious if used moderately — Other factors affecting losses 
by denitrification — The lasting effect of stable manure — 
Manure profitably supplemented by chemical fertilizers — 
Factors governing the use of manure and chemicals — The 
use of coarse manures — Reason for even spreading of 
manure — Manure favors the disintegration of old sod. 

CHAPTER VI 
Sea-weeds 65-74 

The value of sea-weed known to the ancients — Chemical 
composition of sea- weeds — The composition varies at dif- 
ferent seasons of the year — Sea- weed of chief importance 
in New England — The value of eel-grass — Value limited 
by distance of land — Practical utilization — Effect on the 
quality of certain crops — Sea- weed quick in its action — 
Sea- weed compared with farm-yard manures — Not a well- 
balanced manure — Sea-weed as affecting the need of lime 
— Freedom from weed seeds a great advantage — Com- 
posting sea-weeds — Size and rapidity of growth of sea- 
weeds. 

CHAPTER VII 
Guanos 75-85 

Experimental trials of guano — Commercial introduction 
into Europe — The general nature of guano — Chemical 
composition of guanos — Chemical composition affected 
by climatic conditions — Color and physical character — 
Chincha Island guano — Significance of oxalic acid and 
oxalates in guano — Influence on the physical character of 
soils — The distribution and sources of guano — Adultera- 
tion of guano — Rectified or dissolved guano — The man- 



Xll 



CONTENTS 



ner of vising guano — A poorly balanced manure — Bat 
guano unlike Peruvian and other guanos — Appearance 
of bat guano — Where found — Chemical composition — 
Distribution — Precautions in the use and purchase of 
bat guano — Bat guano needs supplementing. 



CHAPTER VIII 

Fish, Crab, Lobster, and Similar Wastes 

Fish long used as a fertilizer — Early catching of fish 
for fertilizer purposes — Special process for preparing 
fish for fertilizer — Fish waste in Japan — In Newfound- 
land — Norwegian wastes from cod and whales — Meth- 
ods of handling menhaden in the United States — Fish 
waste treated with sulphuric acid — Chemical composi- 
tion and utilization of whale products — Availability and 
use of fish guano — Requires supplementing — Fish scrap 
may be employed without further treatment — Value of 
fish waste depends on the climate and soil — Shrimps — 
The king-crab — The common crab — Lobster refuse — 
Star-fish. 

CHAPTER IX 



86-93 



Common Slaughter-house Nitrogenous Waste Products 94-102 

Dried meat meal — All readily utilized by fertilizer 
manufacturers — Chemical composition of meat meal — 
Availability of meat meal — The nature of bone tankage 
— Composition of bone tankage — Value of bone tank- 
age as a fertilizer — Method of employment — Chemical 
composition of red dried blood — Chemical composition 
of black dried blood — Reason for occasional low nitro- 
gen content of blood — Chemical composition of the 
better commercial blood — Crystallized blood — Certain 
processes of preparing dried blood — Dried blood, if very 
fine, is highly hygroscopic — Availability of blood de- 
pendent upon soil conditions — Processes of preparing 
horn meal and hoof meal — Chemical composition of 



CONTENTS Xlll 



horn meal — Chemical composition of horn and hoof meal 
— The nitrogen content of hoof meal — Efficiency of 
hoof meal — Adulteration of horn and hoof meals — Pre- 
paratory treatment of waste leather — The chemical 
composition of prepared leather waste — The availability 
of nitrogen in leather — Treatment of leather with car- 
bonates of the alkalies — Leather really not so valuable 
as it appears. 

CHAPTER X 

Other Miscellaneous Nitrogenous Substances . . 103-112 
Feathers — Hair bristles and wool — Tannery hair — 
Waste silk — Wastes from hares and rabbits — Chemical 
composition of waste wool — Wool waste as a manure — 
Effect of superheated steam on wool waste — Concern- 
ing Petermann's tests of availability — Soluble wool waste 
not subject to loss by leaching — Benefit from steaming 
not equally applicable to all other nitrogenous wastes — 
The value of garbage tankage low — Character of shoddy 
and felt refuse — Chemical composition of shoddy 
and felt — Use of felt and shoddy wastes as manures — 
Character of soot — Chemical composition of soot — 
Soot benefits physically — Soot rarely toxic — Light soot 
best — Insects and cocoons — Peat and muck — Peat and 
muck especially valuable on light soils — Salt and fresh 
muds — Cereal and other seed by-products — Composition 
of cotton-seed meal — Composition of linseed meal — 
Composition of malt sprouts — Composition of castor 
pomace — Composition of wet brewer's grains — Compo- 
sition of gluten feeds — Utilization of the spent wash 
of distilleries — The process of Vasseux — The process 
of Effront. 

CHAPTER XI 

The Availability of Organic Nitrogen and Factors 

Affecting it ....... 113-124 

The factors of temperature and moisture — Effects on 
the soil reaction — Effects of large applications at the 
outset — Employment of different amounts of nitrogen 



XIV 



CONTENTS 



— Other elements must be supplied generously — False 
conclusions a result of neglect of conditions — Results 
by Eckenbrecher — Results by Kellner — Results by 
Petermann — Precautions suggested by Wagner and 
Dorsch — Results of tests by Wagner and Dorsch — Re- 
sults by Wheeler and Hartwell — Results by Voorhees 

— Results by Kellner on wet soil — Results by Seyffert 

— Results by Heinrich — Results by Johnson — Results 
by the nitrification method of Miintz and Girard — The 
pepsin method — The permanganate method — Lipman's 
ammonification method. 

CHAPTER XII 

Calcium and Potassium Nitrates ..... 
Calcium nitrate a new fertilizer — Production possible 
due to cheap electricity — The work of Lovejoy and 
Bradley — The process of Birkeland and Eyde — First 
product too hygroscopic — Processes for lessening hy- 
groscopic tendency — Chemical composition — Calcium 
nitrate as a fertilizer — Danger of the earlier products 
injuring horses and workmen — Extent of the output of 
calcium nitrate — Cost of producing calcium nitrate — 
Other processes — Sources of potassium nitrate — 
Artificial niter beds — Made for industrial purposes from 
nitrate of soda — Potassium nitrate often economical for 
agricultural use — Chlorin avoided by using potassium 
nitrate. 

CHAPTER XIII 



125-131 



Nitrate of Soda ........ 

Sources of nitrate of soda — Concerning the origin of 
the Chilian nitrate of soda — The first exploitation of 
nitrate of soda — Chemical composition and purification 
of nitrate of soda — Impurities of nitrate of soda — 
Physical characteristics of nitrate of soda — The availa- 
bility of nitrate of soda as plant food — Quantities to 
apply and care in using — Nitrate of soda corrects soil 



132-146 



CONTENTS XV 



acidity — Physical effects of the residue from nitrate of 
soda — The residual soda may liberate potash — Re- 
sidual soda may replace potash in part — The soda of 
nitrate of soda may in certain cases conserve the soil 
potash — Soil improvement by using nitrate of soda — 
Nitrate of soda may injure certain soils — Residual bene- 
fit not due solely to hygroscopic effects — Soda as a car- 
rier of phosphoric acid into plants — Nitrate of soda 
conserves the lime supply of the soil — Nitrate of soda 
not a stimulant — Yields quick returns on the manurial 
investment — Possible effects on the microorganisms of 
the soil — Ammonium nitrate — The synthetic produc- 
tion of ammonia and ammonium salts. 



CHAPTER XIV 

Ammonium Salts and Calcium Cyanamid . . . 147-164 

The manufacture of ammonium sulfate — Thiocya- 
nates a former toxic impurity of ammonium sulfate — 
Chemical composition of sulfate of ammonia — Sulfate 
of ammonia must not be mixed with alkaline substances 
— Absorption of sulfate of ammonia by soils — Its use 
exhausts soils of lime — Nitrogen of sulfate of ammonia 
fixed by microorganisms — Its efficiency as a fertilizer — 
Soda important in trials of nitrate of soda and sulfate of 
ammonia — Double decompositions follow the use of am- 
monium salts — Partial soil sterility sometimes caused 
by sulfate of ammonia — Conditions caused in acid soils 
by sulfate of ammonia not fatal to all plants — Aids in 
rendering certain grasses dominant — May cause the 
suspension of certain bacterial activity — Sulfate of am- 
monia liberates plant food — Ammonium salts fleeting in 
their effects — Leach less quickly than nitrates — May 
cause injury on light calcareous soils — Ammonia may 
injure plants — Calcium cyanamid a new product — 
Manufacture of calcium cyanamid — Changes in cal- 
cium cyanamid resulting in the soil — Utilization for the 
manufacture of urea and other substances — As a ferti- 



xvi CONTENTS 



lizer — Practical difficulties connected with calcium cy- 
anamid — The output of calcium cyanamid. 

CHAPTER XV 

Natural Phosphatic Fertilizers 165-190 

Bone as a fertilizer — Chemical composition of bone 
— Composition of the ash — Composition of weathered 
bones — Treatment of bone for the removal of fat — 
Effect of steaming on the nitrogen content — Bone wastes 
from industries — Fermentation and other methods of 
disintegrating bone — Bone meal as a fertilizer — The 
soluble and reverted phosphoric acid of bone — Bone 
tankage — Fish as a source of phosphoric acid — The 
nature of floats — Soils on which to use floats — The ac- 
tion of manure on floats — How floats should be used — 
Liming in connection with the use of floats — Apatite 
or phosphorite — Chemical composition and occurrence 
of apatite — Wagnerite — Coprolites — Phosphatic 
guanos — Nassau or Lahn phosphate — French, Belgian, 
and Portuguese phosphates — The phosphates of Russia 
and Northern Africa — The phosphates of South Caro- 
lina — Florida phosphates — Tennessee phosphates — 
Phosphates of the Western States — Occurrence and 
composition of certain aluminum phosphates — Roasting 
increases the efficiency of aluminum phosphates — The 
solubility of artificial aluminum phosphates — Iron phos- 
phates formed in soils — Solubility of artificial ferric 
phosphate. 

CHAPTER XVI 

Manufactured Phosphates and Studies of Solubility 191-227 
The manufacture of basic slag meal — Influence of 
silica on the efficiency of basic slag — Range in composi- 
tion of low and high grade basic slag — German methods 
of determining availability — The degree of fineness — 
Chemical composition of basic slag — The constitution 
of basic slag — Practical use of basic slag meal — Care 
in mixing basic slag with certain other materials — Arti- 



CONTENTS XV11 

PAGES 

ficial basic slag meal — Wiborgh phosphate — Wolter's 
phosphate — Palmaer phosphate — Other artificial phos- 
phates — The preparation of superphosphates — Treat- 
ment of bone with small amounts of sulfuric acid — Free 
phosphoric acid in superphosphates — Strictly chemical 
use of the term "phosphoric acid" — The relationship 
of the various phosphates — Care in the manufacture of 
superphosphates — Practical process of making super- 
phosphates — Double superphosphates — Dissolved bone 

— Dissolved bone-black — Laboratory studies on the 
solubility of phosphates — The action of water on mono- 
calcium phosphate — The action of water on dicalcium 
phosphate — The action of water on tricalcium phosphate 

— Determination of "soluble" phosphoric acid — Ad- 
vantages of soluble phosphoric acid — The reversion of 
monocalcium phosphate — Liming after reversion with 
iron and aluminum oxids — The determination of re- 
verted phosphoric acid — Reverted phosphoric acid not 
all from dicalcium phosphate — The term available phos- 
phoric acid — Insoluble phosphoric acid — The reversion 
of monocalcium phosphate — Reversion often beneficial 
in some respects — Reversion with iron and aluminum 
oxids serious — Reversion as affected by pyrite — The 
fixation of superphosphates in soils rapid — Fixation of 
phosphates confined chiefly to the surface soil — Availa- 
bility of fixed phosphates may still be high — Injury from 
applications of superphosphates rare — Soils on which 
superphosphates may give poor results — Superphos- 
phates have a flocculating action on soils — Various soil 
conditions affecting the choice of phosphates to be used 

— Crops and conditions for which superphosphates are 
especially adapted. 

CHAPTER XVII 

Potassic Fertilizers 228-245 

"Wood ashes and lime-kiln ashes — Cotton-seed hull 
ashes — Saltpeter waste — Other wastes containing pot- 
ash — Potash from sea-weeds and other plants — Anal- 



xviii ' CONTENTS 



yses of sea-weeds — Tobacco stems — Indian corncobs 
— Potassium nitrate — Potassium carbonate — History of 
the German potash deposits — Americans buy a German 
potash mine — The famous potash contracts — Mode of 
occurrence and distribution of potash deposits in Europe 

— Chemical composition of the more important potash 
salts — Duration of the deposition of potassium salts — 
Natural deposits of potassium salts elsewhere — Kainit 

— Sylvanit and carnallit — Muriate of potash — High- 
grade sulfate of potash — Double sulfate of potash and 
magnesia, or double manure salt — Double carbonate of 
potash and magnesia — Silicate of potash — Potassium 
carbonate (pearl ash) — Greensand — Phonolite, nephe- 
line, alunite, leucite, and feldspars as sources of potash. 

CHAPTER XVIII 

The Theory and Practice of Potash Fertilization . 246-260 
The alleged ill effects of the chlorin of potassium and 
other salts — Reasons for the diversity of ideas concern- 
ing chlorids — Use of chlorids increases the need of 
liming — The fate of sulfate of potash in the soil — Con- 
cerning the retention of potash by soils — Teachings of 
the Rothamsted investigations — Various factors affect- 
ing absorption — Potassium essential to plant growth — 
Potassium aids carbohydrate foi'ination — Other func- 
tions of potassium — Potassium increases the size of the 
individual grains of cereals — Effect of potassium on 
photosynthesis — Potassium in connection with turgor 

— Functions of potassium not necessarily shown by re- 
sults which its absence produces — Potassium as a neu- 
tralizer and carrier within the plant — Potassium may 
contribute to the "luxury consumption" of plants — 
Certain functions and effects of potassium salts in soils 
■ — Effect of potassium salts on legumes — Effect of a 
lack of potassium on grasses and other plants — Potas- 
sium salts act best in wet seasons — Lack of potassium 
more serious for some crops than for others — Potash 
conservation in the soil by sodium salts. 



CONTENTS XIX 

CHAPTER XIX 

PAGES 

Lime and its Relation to Soils and Fertilizers . . 261-294 
The occurrence of lime — Distribution and effect 
of limestone — Kinds of lime used in agriculture 
— The effect of lime on nitrogen availability — The 
effect of lime on denitrification — The effect of lime on 
soil texture — The use of lime in connection with phos- 
phates — Lime as a destroyer of worms and slugs — 
Need of liming suggested by soil acidity — Liming the 
most economic basic treatment — Chemical methods for 
determining the lime requirements of soils — Effect of 
lime on vegetable decay — Effect of lime on nitrogen 
content of humus — Rational rotation and the turning 
under of sward should accompany liming — Avoidance 
• of liming to conserve humus, not wise — Carbonate of 
lime versus slaked or burned lime — The penetration of 
lime into soils — Expulsion of ammonia from soils as a 
result of liming — Influence of lime on nitrification — 
Effect of calcium and magnesium carbonates on ammon- 
ification — General ideas as to the indirect manurial 
action of lime — -Results with sodium and magnesium 
salts illustrate how lime acts indirectly — Fixation of 
potash after liberation by lime — Caustic lime attacks 
powdered quartz — Losses of lime by leaching — Coarsely 
ground limestone compared with fine limestone and marl 
— Concerning the practical use of lime — Pure lime com- 
pared with magnesian lime. 

CHAPTER XX 

Liming in its Relation to Plants 295-308 

Plants may transform lime compounds — Miscellane- 
ous effects of lime on plant diseases — Lime in connec- 
tion with potato scab — Lime may be used and potato 
scab avoided — Lime may cause injury to pineapples — 
Effect of lime on the size of potatoes — Liming may 
hasten crop maturity — Soils needing liming for some 
plants ideally adapted to others — Details concerning 
the lime requirements of different plants. 



XX 



CONTENTS 



CHAPTER XXI 

Gypsum and Waste Lime from Industries 

Early use of gypsum — Source of some of the gypsum 
in soils — Gypsum poorer than lime on acid soils — Gyp- 
sum may yield calcium carbonate in the soil — Gypsum 
may furnish lime or sulfur as plant food — Factors de- 
termining the choice between gypsum and lime — Gyp- 
sum as a retainer of ammonia — Methods of applying 
gypsum — Gypsum as an oxidizing agent — Gypsum may 
sometimes aid nitrification — Gypsum a renovator of 
alkaline soils — Effect of gypsum on the solubility of 
lime — Gas-lime and lime from other industries. 



PAGES 

309-315 



CHAPTER XXII 

Magnesia as a Fertilizer ...... 316-332 

Functions of magnesia in plants — Conflicting ideas as 
to the action of magnesia — Loew's theory concerning 
magnesia — Ratios of lime and magnesia in different 
soils — Variations in magnesia content of different parts 
of the same plant — Concerning the alleged toxic action 
of magnesium chlorid — Danger from using caustic mag- 
nesia and burned and hydrated magnesian lime — Solu- 
bility of magnesium carbonate in its relation to practice 
and experiment — Ranges in lime and magnesia content 
of plants without material difference in yield — Desirable 
lime and magnesia ratios in soils and culture solutions 
— Sources of magnesia. 

CHAPTER XXIII 

Sodium Salts 333-350 

Mineral sources of sodium salts — Black alkali — Quan- 
tities of common salt injurious to crops — The presence of 
soda in plants — Sodium salts as indirect manures — 
Concerning the benefit to crops from applying sodium 
salts — The effect of sodium salts dependent on various 
conditions — Influence of sodium salts on the conserva- 
tion and movement of soil moisture — The effect of 
sodium salts on osmotic pressure — The possible phys- 



CONTENTS Xxi 

PAGES 

iological and manurial functions of sodium salts — Re- 
sults by Jordan and Genter — Soda in connection with 
diastatic action — Atterberg's experiments with soda — 
Experiments at Bernburg, Germany — The Rhode Island 
experiments — Practical significance of soda in agri- 
culture. 

CHAPTER XXIV 

Iron and Manganese 351-356 

Iron in its relation to plant growth — Manganese in 
plants and soils — Manganese as a fertilizer — Manganese 
in Hawaiian soils — Plants unlike in endurance of manga- 
nese — Variations in manganese content of plants — 
Effect of manganese on enzymes — Manganese increases 
many crops — Roots change the oxidation of manganese 

— Manganese may aid chlorophyl development. 

CHAPTER XXV 

Chlorin, Sulfur, Silica, Carbon Disulfid, Toluene, 

and Other Miscellaneous Substances . . . 357-366 

Chlorin — Sulfur — Sulfur may become depleted in 
soils — Relation of sulfur and phosphorus in plants and 
soils — Need of sulfur should be investigated — Silica in 
plants — Suggested functions in plants — Silica may re- 
place other ingredients in the " luxury consumption " — 
Silica deposition checks sap diffusion — Carbon disulfid 
often increases crops — Reasons suggested for the benefit 
to soil from using carbon disulfid — Treatment of soils 
with carbon disulfid costly — Carbon disulfid cures cer- 
tain vetch, clover and alfalfa "sick" soils — Carbon 
disulfid not the only unusual compound to benefit soils 

— Disinfectants, like heating, destroy soil amebe — De- 
struction of soil protozoa may explain benefit from soil 
"firing" and deep plowing — General applicability of 
soil disinfection doubted by Loew — The chlorid of lime 
treatment of soil tried by Loew. 



Index 



367 



FERTILIZERS 

CHAPTER I 

HISTORICAL INTRODUCTION 

According to the earlier conception of the term 
"'manure," it meant anything which when applied to 
the soil will render it more productive. In fact, certain 
very early English writers referred to the benefits of 
tillage as a manuring of the land. 

The use of the dung of animals, and of chalk, marl, 
wood-ashes, and certain other substances for increasing 
the productivity of the soil, was known not only to the 
early Greeks and Romans but apparently also to the 
Chinese, whose employment of them for such purposes 
probably far antedates all human records. 

Indeed, Mago, the king of Carthage, in his work on 
agriculture, which won for him from his enemies, the 
Romans, the designation "Father of Agriculture," wrote 
of the value of bird manure, praising especially that of 
pigeons, and Cato (born 234 B.C.), the first Roman agri- 
cultural writer, gave to bird manure the first place. 

The manurial effect of various miscellaneous substances, 
and of certain legumes, was also well recognized not only 
by the agricultural writers Varro (39 B.C.) and Columella 
(50 a.d.), but even by the poet Virgil, for the latter, in 
speaking of ashes and dung, says : — 

" But sweet vicissitudes of rest and toil make easy labor, and 
renew the soil. 

" Yet sprinkle sordid ashes all around, and load with fattening 
dung the fallow ground." 

b 1 



2 ' FERTILIZERS 

During the dark ages, following the decline of the 
Roman Empire, practically all records of the use of lime 
and of other manures are lacking. The knowledge of 
their value was, however, presumably perpetuated by the 
studious inmates of the monasteries. Already in the 
sixteenth century a revival of the knowledge of manuring 
had begun, as shown by the writings of Bernard Palissy. 

Even Jethro Tull, the early English writer who con- 
tended that manures are unnecessary if the land is suffi- 
ciently tilled, was hardly more radical in his day than a 
certain recent writer who asserted that the chief func- 
tion of fertilizers was to improve the physical condition, 
and later, that it was to render innocuous various toxins 
of the soil. 

1. Chemistry throws new light on the subject of manur- 
ing. — A true understanding of the fundamental princi- 
ples of manuring was made possible only through the 
aid of chemistry, although more or less general specula- 
tion on the subject had long existed, a fact well illustrated 
by many of the earlier English agricultural writings. 

One of the first steps toward a rational understanding 
of the problems of plant nutrition was the discovery by 
Priestley, in 1772, that combustion and the respiration of 
animals deteriorate the air and lessen its volume, but 
that plants can render it again capable of supporting com- 
bustion. This observation, coupled with his discovery of 
oxygen, led to the recognition of the fact that the bubbles 
already observed by Bonnet on leaves when they were 
immersed in water, were chiefly oxygen. It was then 
shown by Ingenhaus that these phenomena were caused 
by the action of sunlight, and Sennebier established the 
fact that the oxygen evolved by plants resulted from the 
decomposition of the carbon dioxicl already taken up from 



HISTORICAL INTRODUCTION 3 

the air, a fact demonstrated in a quantitative way by 
De Sassure. The last investigator showed that carbon, 
associated with the elements of water in the proportions 
represented by carbohydrates, such as starch and sugar, 
constitute the chief weight of plants. It was De Sassure, 
likewise, who recognized nitrogen as a plant constituent, 
and also the source and value of the ash ingredients. He 
supposed that the element nitrogen was derived either 
from the organic constituents of the soil or from ammonia 
present in the air. The idea that the ash constituents are 
of special value to the plant was also held by Sir Humphrey 
Davy. 

Several writers, including Thaer, added their contribu- 
tions to the accumulated knowledge of plant nutrition; 
but it remained for Boussingault to make the first syste- 
matic field experiments. His carefully conducted re- 
searches substantiated the accumulation of far more 
carbon in the plants than could have been derived from 
the soil. He also showed that more nitrogen was removed 
in the crops than was supplied in the manure. 

2. The views of Liebig. — Notwithstanding the inves- 
tigations of those who had preceded him, Justus von 
Liebig soon became the great central agricultural figure, 
for in 1840 he maintained that if plants are supplied with 
the small quantity of mineral constituents of the ash, the 
remainder of their substance can be drawn from the air. 

It appears that Liebig was in error concerning the 
equal importance of the elements of the ash, also as con- 
cerns the analysis of the ash being a safe guide in manuring, 
and in respect to the mode of assimilation of the nitrogen. 
He also erred as to the possibility of certain elements 
replacing others which were somewhat similar, as, for 
example, in the supposed possibility of the complete 



4 FERTILIZERS 

replacement of potassium by sodium. It is now of interest 
to note, however, that the latest researches on this subject 
by Wilfarth and his co-workers in Germany, and by 
Wheeler and Hartwell and their co-workers in Rhode 
Island, uphold the idea of the partial replacement of 
potassium by sodium, in connection with the whole or a 
part of some one or more of its functions in the case 
of at least certain classes of plants. Another question 
concerning which Liebig was gravely in error was that of 
the nitrogen supply of plants. He supposed, with others, 
that the amount of ammonia in the air was much greater 
than is actually the case, and that this supply was main- 
tained or even augmented with great practical benefit 
by the ammonia escaping into the air in the course of 
the fermentation of nitrogenous manures. It was in 
fact in this way that Liebig supposed that such manures 
were helpful to plants. 

3. The early work of Lawes and Gilbert. — Many of the 
views expounded by Liebig were discredited by John Ben- 
nett Lawes (later knighted) of Rothamsted, England, who 
made a number of experiments on his own account. 

When in 1843 John Bennett Lawes associated with 
himself Dr. Joseph Henry Gilbert, a former student of 
Liebig's, he took the first great step in systematic agri- 
cultural experimentation by the establishment of the 
Rothamsted experiment farm, upon which they conducted 
the painstaking researches which have become classic 
in the annals of agriculture. The subsequent experi- 
ments at Rothamsted, in which the American, Pugh 
(afterwards President of the Pennsylvania State College), 
was associated, appeared to disprove the supposed assim- 
ilation of atmospheric nitrogen which Ville and others 
believed to have observed. In fact, in the course of the 



HISTORICAL INTRODUCTION 5 

experiments at Rothamsted in which the soil was sterilized, 
without thought of the consequences, it was concluded 
that the gain in nitrogen by legumes was due merely to 
their great feeding range by virtue of sending their roots 
so deeply into the soil, — a conclusion which for several 
years received world-wide acceptance. 

4. Assimilation of atmospheric nitrogen by plants. — 
Notwithstanding the general acceptance of the idea that 
plants could not assimilate nitrogen directly from the air, 
the fact was nevertheless shown by Atwater l in 1884 in 
experiments with peas, which were grown in unsterilized 
soil in pots under such conditions that subsoil was elimi- 
nated, and not only all of the nitrogen of the soil, 
seed, and fertilizers was known, but also the nitrogen 
in the resulting plants could be determined definitely. 
Similar experiments were in progress at the same time by 
Hellriegel and Wilfarth 2 at Bernburg, Germany, which 
supported fully the conclusions of Atwater. The German 
investigators went indeed far beyond all who had preceded 
them and, by a series of experiments extending over a" 
period from 1883 to 1888, established the fact that such 
assimilation of atmospheric nitrogen is due to the inter- 
vention of microorganisms existing in symbiotic relation- 
ship in the nodules on the roots of certain legumes. It 
has since been shown that even a few plants belonging to 
other families, as, for example, the alder, also assimilate 
atmospheric nitrogen. 

5. Other facts established by Lawes and Gilbert. — The 
honor nevertheless belongs to Lawes and Gilbert of estab- 
lishing the dependence of many of the common agricul- 

1 Am. Chem. Jour., 6 (1884-1885), pp. 365-388. 

2 Untersuchungen iiber die Stickstoffnahrung der Gramineen und Le- 
guminosen, Berlin, 1888. 



6 ' FERTILIZERS 

tural plants on a supply of combined nitrogen, — a fact 
confirmed by the close relationship of the yields to the 
quantities of this element added in available form to the 
soil. It had been held, on the contrary, by Liebig that 
certain very leafy plants, represented by the common 
root-crops and clover, can flourish independently of 
nitrogenous manures (a fact since established for the 
clovers), and are able to draw their supply from the nitro- 
gen of the air. The field experiments of Lawes and 
Gilbert also demonstrated the prime importance of potash 
and phosphoric acid as manures, in contrast with the other 
constituents of the plant ash. These conclusions were of 
fundamental importance to agriculture and paved the way 
for the development of the present enormous fertilizer 
industry. Other experiments in progress at the same 
time by Boussingault, Stohmann, and Knop on the growth 
of plants in various nutrient solutions supplemented the 
work at Rothamsted and placed the question of plant 
nutrition on a substantial and scientific basis. 

It is an interesting fact that by this work of various 
investigators in the preceding century there was afforded 
the first satisfactory explanation of the beneficial effect 
following the addition to the soil of a whole series of waste 
nitrogenous materials and substances of other kinds, the 
utilization of which, in connection with crop production, 
was recorded in England as early as 1653, and had no 
doubt been known already for many centuries. 

6. The utilization of nitrates and guano. — The im- 
portation of nitrate of soda and of Peruvian guano into 
England for manurial purposes was begun about 1838 
and 1840 respectively, although the value of nitrate of 
potash in connection with the growth of crops was surely 
known as early as 1669. 



HISTORICAL INTRODUCTION 7 

7. Employment of ammonium salts. — The ammonium 
salts were supposedly first employed as manures as a 
result of the work and writings of De Sassure and Liebig 
on the utilization of ammonia by plants. Their use by 
Lawes, however, antedates the appearance of Liebig's 
memorable paper on the subject in 1840. The systematic 
trials of a mixture of ammonium chlorid and of ammonium 
sulfate at the Rothamsted experiment station date from 
the year 1843. 

8. The manufacture and use of superphosphate. — 
The employment of mineral phosphates, in a limited way, 
was begun in 1842 when Lawes took out his patent for 
the manufacture of superphosphate, but they were not to 
be had in any considerable quantity until three years 
later, when coprolites were discovered in England. 

9. The German potash salts. — It is a noteworthy 
fact that the common salt manufacturers in certain parts 
of northern Germany were long troubled by supposedly 
worthless materials consisting of mixtures of crystalline 
salts of potassium chlorid, potassium sulfate, and corre- 
sponding salts of calcium and magnesium which were 
associated with some common salt and were found over- 
lying the purer rock-salt deposits. These materials were 
considered so objectionable and they interfered so se- 
riously with the common salt manufacture that they were 
given the collective name of " Abraumsalz," which desig- 
nates something to be taken out of the way. In or about 
the year 1860, however, the use of these salts for agri- 
cultural purposes was begun, — a step which has led to the 
present enormous output of kainit, muriate of potash, 
double manure salt (chiefly sulfate of potash and sulfate 
of magnesia), and of high-grade sulfate of potash, the 



8 FERTILIZERS 

world's supply of which practically all comes at present 
from the German mines. 

10. The manufacture of basic slag meal. — Another 
notable advance in the development of the fertilizer in- 
dustry resulted from the discovery in 1879 by Thomas and 
Gilchrist, in England, of a method by which phosphatic 
iron ore could be effectively freed of its phosphorus in 
connection with the Bessemer process for the manufacture 
of steel, and whereby the resulting phosphatic slag was 
transformed into a valuable fertilizer. It has been stated 
that the same process was discovered independently by 
Jacob Reese in the United States. This phosphatic by- 
product is known under the names " Thomas phosphate," 
" Thomas meal," " basic slag meal," and the like. The 
use of this material has already reached enormous pro- 
portions in Europe, and it is being exported in considerable 
quantities to America, Egypt, and elsewhere. 

11. New processes for combining atmospheric nitrogen. 
— Another important advance in 'the fertilizer industry 
has been brought about by the recent discovery by Frank 
and Caro, of Berlin, Germany, of commercially successful 
methods for. the manufacture of calcium cyanamid by 
the utilization and combination of atmospheric nitrogen 
through the agency of calcium carbide. 

A still further step in advance in connection with the 
nitrogen fertilizer problem has resulted as a consequence 
of the discovery of a method by Berkeland and Eyde by 
which, by the aid of a powerful electric current, atmos- 
pheric nitrogen can be combined and united with calcium 
to form calcium nitrate. In Germany a process has also 
been devised by which hydrogen and nitrogen gases are 
made to unite under pressure and form ammonia by the 
aid of catalytic agents. 



HISTORICAL INTRODUCTION 9 

12. New catalytic and other fertilizers. — Space will 
not permit the mention of the many other new processes 
for the treatment of low-grade crude phosphates, feldspar, 
and similar materials, in order to increase their avail- 
ability, and of the series of so-called catalytic fertili- 
zers, such as certain manganese and zinc salts. 

Whereas it has seemed with each new discovery that 
the limit of human invention and accomplishment might 
have been reached, the recent progress doubtless only 
foreshadows still greater steps in the immediate future. 



CHAPTER II 

NIGHT SOIL 

The term " night soil " has long been applied to human 
excrement for the reason that it was often customary, 
before the introduction of sewers, to remove it from 
cities and towns during the night. 

Human excrement is exceptionally rich in nitrogen 
and phosphoric acid. This is due not only to the nature 
of the food consumed, but also to the high degree of diges- 
tibility of the non-nitrogenous constituents of the diet, 
as compared with the coarser feeds consumed by the do- 
mestic animals. By the fermentation of the excrement 
great losses of nitrogen may result. 

13. Conservation of night soil now less necessary. — 
Owing to the rapid consumption of the natural supply of 
nitrate of soda, the fear was expressed quite recently 
that through the drain upon the land occasioned by the 
great numbers of people living in cities, and the almost 
universal waste of their excrement in the sewage, a 
nitrogen famine might result. Fortunately, this fear 
has been dispelled by the more recent discovery of 
economical methods for the production of calcium 
cyanamid, calcium nitrate, and ammonia from the in- 
exhaustible supplies of limestone, atmospheric nitrogen, 
and hydrogen. 

Danger to health. — One of the great objections to the 
use of human excrement as a manure is that it is often a 

10 



NIGHT SOIL 11 

great source of danger, on account of its being a ready 
medium for the conveyance of the organisms which 
cause various types of human disease. The necessity 
of providing a safe place for the deposition of human 
excreta at a distance from the abiding place of man, 
is even set forth in the Bible Deuteronomy 23, verses 
12 and 13). 

14. Amount of urine produced per person. — Ac- 
cording to Heiden, a single individual produces in the 
course of the year about 1000 pounds of excrement, 
having a usual fertilizing value of from two to three 
dollars. 

It was found by Lecanu, in experiments with sixteen 
persons of different ages and sexes, that the excretion of 
urine, per twenty-four hours, ranged from 525 to 2271 
grams. In experiments conducted on himself, Lehmann 
found, in a fourteen-day test with a mixed diet, that the 
daily excretion of urine amounted to from 879 to 1384 
grams ; and in the course of a twelve-day vegetable diet, 
it fell to from 720 to 1212 grams. Based upon these and 
other data, it is probably safe to estimate the average daily 
excretion of urine, per capita, at about 1200 grams (about 
4.2 pounds). 

The solid matter in human urine has been found, based 
upon the work of several investigators, to range from about 
34.5 to 87.4 grams per day, though it is said to vary with 
the different nationalities. This variation may, however, 
be due to temperature and other climatic conditions, 
rather than to constitutional differences. 

15. Chemical composition of human urine. — The 
following percentages, given by Lehmann, represent the 
relative quantities of some of the more important con- 
stituents of human urine : — 



12 



FERTILIZERS 



With a mixed diet . . 
With an animal diet 
With a vegetable diet . 
With a nitrogen-free diet 



Urea 


Uhic 
Acid 


32.5 
53.2 
22.5 
15.4 


1.18 
1.48 
1.02 
0.74 



Extractive 
Substances 
and Salts 



12.8 

7.3 

19.2 

17.1 



It appears therefore that the urine varies greatly in com- 
position, as well as in amount, according to the diet of 
the individual. 

It has been found that the percentage of nitrogen in the 
urine of children eight months old is about 0.15; in that 
of men 21 years old, 1.02, and in the urine of men of 46 
years, 1.57 to 1.84. Based upon an average of 1200 grams 
of urine per twenty-four hours per individual, the average 
daily excretion of nitrogen in the urine would amount to 
13.36 grams. 

The quantity of non-combustible salts is least in the 
urine of children, followed in turn by the urine of women, 
aged people, and men. The variations, however, in indi- 
vidual cases, and within these groups are very great. The 
chief constituents of the ash of urine, named in order, are 
chlorin, soda, potash, phosphoric acid, sulfuric acid, 
lime, magnesia, and iron oxid. Slight amounts of in- 
soluble matter make up the remainder. 

16. The amount of solid excrement per individual. — 
The average quantity of solid excrement, per day, as 
found by Lawes and Gilbert, for boys under sixteen years 
of age, was about 108 grams ; for men between 16 and 50 
years, it was about 152 grams ; and for men over 50 years 
of age, about 226 grams. The dry substance ranged 



NIGHT SOIL 



13 



from 27.4 to 42.3 per cent ; it was found to be greatest 
in the case of old men. The amount of nitrogen present 
in the average daily excretion of the solid excrement of 
boys was 2.34 grams, of men 1.94 grams, and of old men, 
0.321 gram. The quantities of ash were 3.69, 4.23, and 
8.32 grams, respectively. In the ash the phosphoric acid 
has been found to range from about 31 to 43 per cent, 
the potash from about 6 to 21 per cent, lime from about 
17 to 27 per cent, and magnesia from about 10.5 to 15.5 
per cent. 

Heiden gives the following as the average quantity of 
both solid and liquid excrement per person daily : — 



Total quantity 

Solid matter ..."... 

Organic matter 

Nitrogen (in organic matter) 

Ash . 

Phosphoric acid (in ash) . . 
Potash (in ash) 



Solid 
Grams 


Liquid 
Grams 


133.0 


1200.0 


30.3 


64.0 


25.9 


50.0 


2.1 


12.1 


4.5 


13.0 


1.6 


1.8 


0.7 


2.2 



Total 
Grams 



1333.0 
94.0 
75.5 
14.2 
17.5 
3.4 
3.0 



17. Former methods of disposal in Europe were bad. — 
In Europe, generally, the conditions connected with the 
disposal of human excrement were, until a comparatively 
recent period, extremely bad, and even after the construc- 
tion of sewers emptying into the most accessible streams, 
the situation became highly dangerous to the public 
health. In England this led to the appointment of a 
special commission to inquire into, and report concerning, 
the matter. As a result of this and of similar agitation in 



14 FERTILIZERS 

other lands, the present efficient septic tank and combined 
precipitation and filtration systems have been evolved. 

18. Orientals conserve human excrement carefully. — 
Japan and China have thus far led the world in the 
systematic saving and use of human excrement for agri- 
cultural purposes. It has been possible thereby in the 
past, not only to maintain the enormous population of 
those countries, which is five to six times as dense as that 
of certain of the chief countries of Europe, but they have 
also been able, since the opening of their ports, to export 
to other countries considerable amounts of human food. 
In view of the practical economies of the Oriental nations 
in this respect ; and in view of the fact that the world 
seemed to be facing a future nitrogen famine, many sys- 
tems for the preservation of human excrement have 
been devised from time to time. Owing, however, to 
the present methods of transforming the inexhaustible 
nitrogen supply of the air into available plant food in an 
economical way, it is unnecessary to devote space here to 
their description, from the standpoint of the conservation 
of nitrogen, more than by way of the briefest historical 
reference. 

19. The conservation of human excrement in Paris. — 
The first police ordinance of the city of Paris, relating to the 
disposition of human excrement in a secret vault or similar 
place in each house, dates from 1348, but it was not until 
1583 that a penalty for such an omission was provided. 
Regulations for the construction of such receptacles were 
made in 1809 by a decree of Napoleon, which was renewed 
in 1819. 

From 1781 to 1849 the human excrement of the city of 
Paris was deposited in an abandoned suburban quarry 
from which source the offensive odors penetrated a con- 



NIGHT SOIL 15 

siderable portion of the city. As a result, provision was 
finally made for its disinfection and for effecting a separa- 
tion of the liquid and solid excrement. The former was 
then conducted into cisterns just outside of the city, from 
whence it was pumped to a more distant point, to which 
the solid excrement was at once conveyed by boat. 
Here the mass was left in open beds for several months. 
After the liquid portion had been clarified, it was utilized for 
the manufacture of ammonia. The remaining solid matter, 
after drying for a time in the beds, was further dried in the 
field, and then sold under the name of " poudrette." A 
part of the excrement was, however, still turned into the 
canals and found its way into the river Seine. 

Still later, after it was found that the method of disposal 
just described was not economical, the Seine became the 
receptacle for the entire mass of this material. The condi- 
tions which arose in consequence were so serious that a 
commission was appointed to investigate the entire subject, 
and, as a result, a modern filtration system was adopted. 

In the meantime in Lyons, in the south of France, 
and here and there in England, attention had already been 
given to saving some of the human excrement for agri- 
cultural purposes. 

The history of the situation in Paris is typical in many 
respects of the steps taken in other European cities, which 
have finally resulted in the present methods of municipal 
sewage disposal. 

20. " Poudrette " from human excrement. — One of 
the products sold under the name of " poudrette " is 
prepared by the Liernur process, which consists in adding 
to the excrement sufficient sulfuric acid to bind the am- 
monia, after which the mass is evaporated in a vacuum 
until it reaches such a consistency that it can be completely 



16 • FERTILIZERS 

dried by other means and finally reduced to a powder. 
It happened, unfortunately, that the tendency to introduce 
foreign material, by way of adulteration, brought such 
poudrette into more or less general ill repute. 

21. Treatment of excrement with burned lime. — 
Another but more wasteful process for the utilization 
of human excrement consists in treating it with burned 
lime. This method is said to have been first proposed by 
Payen and then by A. Miiller, and upon it is based the 
system of Mosselmann and Muller-Schiir. By this pro- 
cess the ammonia which has been formed previously in 
the mass is lost. It is therefore important that the excre- 
ment be treated in as fresh a state as possible. Mossel- 
mann used two parts by weight of burned lime to one of 
moist excrement, and the final volume amounted to two 
and one-half times that of the lime employed. In this 
process 100 parts by weight of lime volatilize about 25 
parts of water and bind chemically and mechanically 
about 50 parts more, thus producing a product which is 
so dry that it can be readily handled and transported, 
and the heat generated is sufficient to destroy pathogenic 
organisms. Such a system was in use recently in con- 
nection with the disposal of the excrement from tenement 
houses in certain manufacturing villages in Rhode Island, 
and the following is the composition of the product thus 
secured : — 

Per Cent 

Calcium oxid 11.28 

Potassium oxid 0.09 

Phosphoric acid 0.91 

Nitrogen 0.43 

One great objection to the material prepared by this 
process is that it is so excessively rich in lime that if it 



NIGHT SOIL 17 

were applied regularly in sufficient quantities to supply 
the soil adequately with the other fertilizer ingredients, 
it would result in liming to excess. It may, however, be 
used frequently, for a time, on soils originally quite acid 
or, more infrequently, on those only moderately in need of 
liming. To meet this objection in part, basic slag meal, 
potash salts, and other chemicals have sometimes been 
incorporated with it before placing it on the market. 

22. The " A. B. C." and other methods of conservation. 
— In the absence of burned lime, alum, blood, and clay 
have been added to the excrement, after which the solid 
matter is dried, ground, and marketed under the name of 
" native guano." This process takes its name " A. B- 
C." from the first letter of the name of each of the materials 
added to the excrement. A large number of other methods 
for the disposal of human excrement, by its transformation 
into poudrette, have been proposed from time to time. 
Some of these, like that of Teuthorn, involve evaporation 
and drying of the mass by natural means, whereas that 
of Thon was based upon evaporation of the water by 
means of artificial heat. The product as prepared by 
Thon at Stuttgart had the following composition : — 

Per Cent 

Nitrogen . 4.5- 6.0 

Phosphoric acid 10.0-12.0 

Potash 1.5- 3.0 

In connection with the many other processes which 
have been employed for the same purpose at various 
times, practically every conceivable absorbent and con- 
serving material has been used. 

23. The novel method of Sindermann. — Among all 
of the methods proposed for the disposal of human excre- 
ment, perhaps the most novel is that of A. Sindermann, 



18 ' FERTILIZERS 

which was adopted in connection with a hotel in Breslau, 
Germany. The excreta in this case were placed in a 
retort, where they were not only dried, but also subjected 
to dry distillation, in the course of which there were pro- 
duced illuminating gas, carbon dioxid, tar, oil, and am- 
monia. The valuable products were saved, as in the manu- 
facture of gas from coal ; the gas, after the removal 
of the carbon dioxid and subjection to other purification, 
was used for illuminating purposes in the hotel. The 
resulting ash, with a content of 5.57 per cent of water, 
was found to contain 6.5 per cent of lime, 3 per cent of 
magnesia, 5.5 per cent of potash, and 8.6 per cent of phos- 
phoric acid. 

24. Repeated use encourages undue leaf growth. — 
In general, it may be said that the continued use of con- 
siderable quantities of human excrement on land leads 
to unusual leaf growth, and, in the case of grass land, 
causes the lodging and consequent molding of some of the 
crop. Its excessive use also results in delaying the fruiting 
of other crops. The economical utilization of such mate- 
rial depends, therefore, upon limiting the amount used to 
that required to furnish the needed nitrogen, and on its 
being supplemented by proper amounts of potash and 
phosphoric acid. 



CHAPTER III 

THE DUNG OF FARM ANIMALS AND ITS PRESERVATION 

The term "farm manure " covers properly the dung of 
all the domestic animals kept on the farm, including the 
customary litter, night soil, peat, muck, leaf mold, other 
vegetable refuse, and composts. Barn-yard manure, as 
usually understood, relates to the dung of neat cattle 
with the usual litter. Stable manure is a term at present 
more commonly applied to the dung and litter from horse 
stables. 

25. Influence of feed and age of animal on dung. 

It may be stated that in general the dung of mature 
animals is of greater value than that of those which are 
making rapid growth; similarly, the dung of cows not 
with calf and especially of those not producing milk, is 
richer than that of animals bearing their young or which 
are yielding large volumes of milk. The reasons for this 
are sufficiently obvious. It is assumed of course in such 
instances that the feeds are of the same general character. 
The dung of animals fed chiefly on grain, milk, and other 
similar materials is richer than that of those which 
subsist chiefly on coarse feeds, since it contains much 
more nitrogen, the most costly of all the manurial ingre- 
dients. 

26. Influence of litter on manure. — The value of 
dung, as it has to be dealt with in a practical way, is very 
greatly affected by the kind and quantity of litter or 

19 



20 FERTILIZERS 

absorbents employed in the stables or yards. For ex- 
ample, the manurial value of cacao refuse or of peat or 
muck is of itself far greater than that of such materials 
as sawdust, shavings, and cotton waste, which are ex- 
ceedingly poor in nitrogen and in other less valuable 
manurial ingredients. 

27. Collecting and caring for dung. — The method of 
collecting and of caring for the dung of the farm animals 
may affect its value greatly. If it is thrown out under the 
eaves of the stable, as was once a too common custom in 
the United States, most of the liquid or more valuable 
portion, representing about four-fifths of its total value, 
is likely to be carried away in the rain water. If, on the 
other hand, horse manure is allowed to lie in an undis- 
turbed pile in a barn cellar and to undergo fermentation 
until it reaches a " fire-f anged " condition, great loss of 
nitrogen inevitably results. Serious, though less exten- 
sive losses of nitrogen occur through volatilization of 
ammonia either in the stable, cellar, or storage shed, on ac- 
count of the failure to use chemical agents for its retention ; 
but more particularly from leaving it either in small heaps 
or spread upon the surface of the ground for some time 
before the land is plowed. 

28. Horse manure. — Because of the fact that the 
horse has but one stomach, and hence does not ruminate, 
it is not as well able as the sheep and cow to completely 
disintegrate and digest coarse feeds. On this account, 
and due to the presence of large amounts of fibrous 
material, horse manure is especially open and porous in 
character. 

Subject to ready fermentation. — On account of the less 
complete destruction of the organic compounds of the hay 
and grain in the course of the process of digestion, horse 



THE DUNG OF FARM ANIMAL 8 21 

manure furnishes abundant organic food for the many 
microorganisms which promote decay, and hence it is 
especially subject to fermentations of various kinds. This 
fact is taken advantage of by its employment for the evolu- 
tion of heat in greenhouses and cold-frames. Owing to 
its loose physical character, horse manure is often mixed 
with cow manure, for certain purposes, with distinct ad- 
vantage to each. 

The solid -portion. — The solid excrement of horses con- 
sists chiefly of the undigested portions of the feed, as- 
sociated with bacteria, minute quantities of biliary matter, 
and epithelial tissue, arising from the normal destruction 
of intestinal surfaces. The average composition of the 
solid manure is as follows: nitrogen 0.55 percent, phos- 
phoric acid 0.30 per cent, and potash 0.40 per cent. 

The liquid portion. — The liquid excrement contains 
soluble phosphates, potash salts, and the organic meta- 
bolic products of the animal, such as urea, traces of crea- 
tinin (C 4 H 7 N 3 0), and, in the case of horses at rest, small 
quantities of hippuric acid. The urine of horses is more 
concentrated than that of the bovine species, and it con- 
stitutes about one-fourth of the weight of the total ex- 
crement. The following represents the average analysis 
of the liquid manure : nitrogen 1.35 per cent, phosphoric 
acid a trace, potash 1.25 per cent. After being added to the 
solid portion the mixture has the following composition : 
nitrogen 0.7 per cent, phosphoric acid 0.25 per cent, and 
potash 0.55 per cent. 

Storage, and the use of litter. — Usually a greater percent- 
age of litter (bedding) is used for horses than for cows, on 
which account the manure as a whole is often of a more 
strawy character. The value of the manure is usually 
considered greater if straw or leaves are used for bedding 



22 FERTILIZERS 

than if either shavings or sawdust is employed. This is, 
however, more likely to be true if the shavings are made 
from the wood of pine and of certain other coniferous trees. 
Experiments are nevertheless on record, showing that cow 
manure has been found to be equally as valuable with saw- 
dust litter as with a litter of straw or chopped corn stalks, 
when used for roses, carnations, chrysanthemums, and 
sweet peas. For certain reasons, manure without litter 
was preferred in special cases. 1 

If horse manure is to be stored before its application to 
the soil, it should be compacted at once as completely as 
possible, and especial care should be taken to keep it moist. 

Amount of manure produced per animal. — It is estimated 
that every 100 pounds of dry matter in the feed of a horse 
will produce about 210 pounds of manure, containing about 
77.5 per cent of moisture. Allowing in addition 6.5 pounds 
of bedding per day per horse, and allowing also for the 
manure usually voided outside of the stall, there would be 
available for use about five and one-fourth to six and one- 
third tons of manure per horse per annum. 

29. Cow manure. — The manure of neat cattle, owing 
to their habit of ruminating and to the comparatively 
complete digestion afforded by their four stomachs, is 
far more compact than horse manure, and hence for many 
purposes is improved by an admixture of the latter. 
Nevertheless, in the preparation of soil for rose culture 
under glass, and for certain other greenhouse, garden, and 
farm purposes it is preferred, by many, unmixed with 
horse manure. 

Chemical composition. — The chemical composition of 
cow manure is much like that of horse manure, though 

!Pub. Int. Agr. Inst. (Rome), Ottawa Branch, Bui. 2, No. 6, July, 
1912. 



THE DUNG OF FARM ANIMALS 23 

it is less concentrated, and it contains about one per cent 
of hippuric acid (C9H9NO3). 

Quantity voided per cow. — The quantity of manure 
voided by the cow is much greater than that produced 
by the horse, which compensates in a measure for the more 
dilute character of the liquid portion, when considering 
the total value of the yearly product of each. The quan- 
tity of manure excreted daily per cow, inclusive of the 
customary quantity of absorbents, is from twenty-five to 
thirty pounds greater than that produced by the horse. 
One pound of dry matter in the feed will furnish about 
3.84 pounds of manure. To this must be added the litter 
in order to show the total amount of manure produced per 
animal. An average cow, if properly fed, will excrete 
approximately 65 pounds of manure per day, about 25 
per cent of which is represented by the liquid portion. It 
is obvious that there will be wide individual variations 
from these figures, dependent upon the weight of the cow 
and upon the character and digestibility of her feed. 

Proportion of the nitrogen voided. — About one-fourth of 
the nitrogen of the feed is appropriated by the cow for 
the manufacture of her milk product, and to replace hair 
and other waste, leaving another and less valuable fourth 
in the solid excrement, and one-half in the liquid manure. 

30. Sheep manure. — The value of the manure produced 
by a single sheep in a year is small. The manure always 
contains less water than that of other domestic animals, 
the average content being about 74 per cent. Sheep 
manure is especially prized by many florists for use in 
greenhouses, due, doubtless, in part to its improvement of 
the physical character of the soil ; it is also much sought 
in some localities for application to lawns and for the pro- 
duction of certain garden crops. Owing to the low water 



24 FERTILIZERS 

content of sheep manure, it is liable to ferment easily and 
to lose some of its nitrogen as ammonia. The average 
composition of the mixed solid and liquid manure is as 
follows : nitrogen 0.95 per cent, phosphoric acid 0.35 per 
cent, and potash 1.00 per cent. 

Amount of manure produced by sheep. — At the Cornell 
agricultural experiment station, it was found that three 
sheep fed for thirty-three and two-thirds days produced 
a total of 723 pounds of solid and liquid excrement. The 
average of a large number of German experiments shows 
that for 100 pounds of dry matter of the feed there are 
recovered 48.4 pounds of dry matter in the excrement. 
In general, the multiplication of the dry matter of the feed 
by 1.88 and the addition of the litter will give approxi- 
mately the amount of manure. On the basis of 73 per cent 
of water in sheep manure, 100 pounds of dry matter of the 
feed would produce 183 pounds of manure ; or, in other 
words, a sheep weighing about 60 pounds would consume 
about 2 pounds of dry matter daily, which, with an amount 
of litter such as is often used, would amount to about 1500 
pounds of manure per year. 

31. Hog manure. — As a rule, hog manure is of less 
interest than that of other domestic animals, for the reason 
that a large portion of it is often voided in the field. It 
varies also so widely in composition, owing to the diversi- 
fied character of the food consumed, that one cannot give 
a value to it within very definite limits. Assuming the 
food to be the same, hog manure will not vary widely from 
the composition of the manure of other animals. The 
average of a considerable number of experiments shows 
that for every 100 pounds of dry matter in the feed con- 
sumed there will be produced about 237 pounds of manure. 
The liquid manure of hogs which have been well fed often 



THE DUNG OF FARM ANIMALS 25 

contains as much as 2 per cent of nitrogen. The solid 
excrement of hogs is very wet and decomposes less readily 
than that of horses and of sheep. 

A hog will void on the average from 12 to 15 pounds of 
manure per day, which is equal to from two to three tons 
per year. 

There seems to have existed among farmers a certain 
prejudice against the use of hog manure for certain crops, 
although there seems to be no satisfactory experimental 
basis at this time for definite statements on this point. 

32. Hen and pigeon manure. — The manure of hens and 
pigeons differs materially from that of the more common 
farm animals, by reason of the fact that the excreta are 
voided in one portion, rather than separately in solid and 
liquid form. 

Chemical composition. — A number of analyses of fresh 
hen manure show the range in nitrogen content to be from 
0.56 to 1.38 per cent; in phosphoric acid, from 0.35 to 
1 per cent, with the majority ranging from about 0.47 
to 0.92 per cent; and the range in potash is from 0.18 
to 0.45 per cent, though the more common limits are 
between 0.25 and 0.4 per cent. 

Air-dry hen manure contains from 1.82 to 2.13 per cent 
of nitrogen, from 0.85 to 2.21 per cent of phosphoric 
acid, and from 0.35 to 1.11 per cent of potash. It is not 
an ideally balanced manure for all purposes, and can usually 
be supplemented profitably by 'the addition of a liberal 
amount of acid phosphate and by a moderate quantity 
of muriate of potash or of kainit. When so employed, 
the results from its use, even in much smaller quantities 
than otherwise, are excellent. 

Both superior in their action. — The superior action of 
pigeon and hen manure may readily be attributed in part 



26 FERTILIZERS 

to the fact that the liquid and solid manure are voided 
together, in consequence of which the metabolized nitro- 
gen is less likely to suffer loss by leaching than in the case 
of most other manures. Furthermore, it very quickly 
undergoes nitrification after its application to the soil. 
These manures are naturally richer in nitrogen and in 
other fertilizer ingredients than certain coarser manures, 
owing to the more concentrated character of the feeds 
consumed. In view of the foregoing circumstance, these 
manures contain less of the various organic materials 
which characterize especially horse manure, and hence 
furnish a smaller supply of the organic foods for the organ- 
isms which are especially concerned in denitrification and 
the liberation of nitrogen in a free state. 

Both manures need supplementing. — The adaptability 
of hen and pigeon manure to general trucking and garden- 
ing purposes would often be much increased, and the 
ammonia better conserved, if 12 to 15 pounds of acid phos- 
phate and 18 to 20 pounds of kainit, or 4 to 5 pounds of 
muriate of potash were added to every 100 pounds of the 
fresh manure. It might be still further improved by add- 
ing to each 100 pounds, 5 to 10 pounds of gypsum, or land 
plaster. 

33. Amounts of litter used as absorbents. — The quan- 
tity of litter which should be used is not only dependent 
upon the class of farm animals concerned, but also upon 
the character of the food consumed ; since watery foods 
and those containing a large amount of nitrogen cause 
an increased flow of urine. It is generally desirable to 
employ sufficient litter to keep the animals clean, by in- 
suring the absorption of the liquid manure. To this end 
it has been recommended that the amount for cattle per 
day should be 9 pounds, for horses 6.5 pounds, and 



THE DUNG OF FARM ANIMALS 



27 



for sheep three-fifths pound. Stated in another way, the 
litter should be equal, approximately, to one-third of the 
dry matter consumed. 

34. Comparative absorbent power of litters for water 
and ammonia. — The ability of the litter to absorb liquid 
may differ widely from its capacity to hold ammonia, as 
shown in the following table : — 



Kinds of Material 


Water Retained 

by 100 Pounds of 

Material after 

24 Hours 

Pounds 


Ammonia Absorbed 
by 100 Pounds of 
Different Ma- 
terials 

Pounds 


Partially decomposed oak 
leaves ....... 

Peat 

Needles of coniferous trees . 

Spent tan 

Air-dried humons soils 
Mosses and forest leaves 


220 

285 
280 

162 
200 
600 
175 
435 
450 
50 
275 

25 


0.17 

i 

1.10 
0.05 
0.66 
0.86 



1 Not determined. 



It will be seen that in proportion to the amount of liquid 
held, air-dried humous soil is a most efficient absorber of 
ammonia. This is no doubt due in part to a chemical 
union of the ammonia with organic acids present in the 
humus, as well as to a similar union with zeolites and pos- 
sibly other complex silicates of the mineral portion of the 



28 ' FERTILIZERS 

soil. As absorbents of ammonia, peat, peat moss, and 
humous soil take the first rank. 

In so far as concerns ability to take up and hold 
water, peat is superior to all of the other absorbents. 

Both loam and peat may be used effectively in bedding, 
as supplements to, and economizers of, straw. 

In a series of tests made with cotton waste at the ex- 
periment station of the Rhode Island State College, it was 
found that 100 pounds of a dyed and quite clean sample 
absorbed 435 pounds of water. The same quantity of an 
undyed lot of similar character absorbed 550 pounds, and 
two other lots, which contained considerable quantities 
of fine foreign matter, absorbed but 267 and 231 pounds 
of water, respectively. 

35. The degree of conservation effected by litters. — 
It was found by Muntz and Girard that where the loss of 
nitrogen from the manure of cows amounted to 59 per 
cent without the use of litter, its addition reduced the 
losses to 50 per cent and 44 per cent. Where excessive 
quantities of litter were employed, the losses were never- 
theless 41 per cent. In their study of the relative effi- 
ciency of straw and peat moss, in the preservation of horse 
dung, it was found that the loss of nitrogen, when straw 
was employed, was 58 per cent ; whereas with peat moss 
it was but 44 per cent. Similar experiments with straw, 
in the preservation of sheep manure, showed a loss of 
50 per cent of the nitrogen, whereas by the substitution of 
a litter of earth, the loss was reduced below 26 per cent. 

36. Losses of manure lessened by packing and tram- 
pling. — Since very early times it has been a common prac- 
tice to pack horse manure, in order to prevent its rapid 
fermentation and consequent " fire-fanging," which, if 
unchecked, results in the loss of most of its nitrogen. 



THE DUNG OF FARM ANIMALS 29 

Similar packing in the case of other manures also mini- 
mizes the loss of nitrogen, as has been shown by numerous 
experiments. 

The compacting of horse manure and cow manure is 
often accomplished in this country and in Europe by con- 
fining swine or other farm animals within the inclosure 
where the manure is stored. 

In Europe it is a common practice to place the farm ani- 
mals in deep stalls, having cemented sides and bottoms. 
They are then littered generously and allowed to remain 
in the stalls for several months on the accumulations of 
manure and litter. When such methods are practiced, 
the usual losses of nitrogen range from about 13 to 18 per 
cent. This loss is occasioned not only through the direct 
volatilization of ammonia, but by the transformation of 
considerable quantities of the more readily soluble and 
available nitrogen into less available forms, through bac- 
terial agencies. The change of available nitrogen into 
more inert forms also accompanies the process of denitri- 
fication; whereby also much of the nitrogen of nitrates 
may, under certain conditions, be liberated as gaseous 
nitrogen. The nitrogen thus rendered inert is transformed 
into what is commonly classified as humous nitrogen, 
a direct product in this case of the destruction of the or- 
ganisms of which it became at first a constituent part. 

It is cited by Hall that in experiments made by Russell 
and Goodwin, 43.83 pounds of digestible nitrogen were fed, 
and but 3.07 pounds of it were retained by the animal 
which consumed the feed containing it. The remainder, 
represented by 40.76 pounds, was voided as urea. Upon 
subsequent examination of the dung, it was found, how- 
ever, that but 28.6 pounds of nitrogen remained in the 
shape of ammonia and amids, and that, aside from a direct 



30 FERTILIZERS 

loss of 7.38 pounds of nitrogen, 4.78 pounds had been 
converted, during the fermentation, into proteins and 
other insoluble compounds. 

It has been found by Maercker and Schneidewind, in 
experiments with steers, that manure properly trampled 
suffers an average loss of about 15 per cent of its nitrogen, 
but that the loss will readily rise to from 30 to 40 per cent, 
if the manure is thrown out into piles daily, or at quite 
frequent intervals. 

The richer the manure in soluble or immediately avail- 
able nitrogen, the greater is likely to be the percentage loss 
of nitrogen during the making and storage, and hence such 
manures should receive most careful attention. 

37. Soil a powerful absorbent of ammonia. — In ex- 
periments performed by Muntz and Girard it was found 
that uncovered cow manure suffered a loss of 142 milligrams 
of ammonia, but that, under otherwise like conditions, 
when covered with soil to a depth of about three-quarters 
of an inch (2 cm.) the loss was but 10 milligrams. Simi- 
larly the loss of ammonia from uncovered sheep manure 
amounted to 1642 milligrams, but with a covering of soil 
like that used with the cow manure, the loss was but 128 
milligrams. In experiments with air-dried sandy soil, 
as a litter for sheep, the loss of nitrogen amounted to but 
25.7 per cent of that consumed in the feed, as compared 
with a loss of 50.2 per cent, when straw was substituted 
for the soil. 

How the soil acts in retaining ammonia. — The reten- 
tion of ammonia by soil is probably due chiefly to three 
causes. The first and least important is its direct absorp- 
tion and retention by the moisture held on the surface of 
the soil particles ; the second is its combination with or- 
ganic acids, arising in the course of the decomposition of 



THE BUNG OF FARM ANIMALS 31 

vegetable debris ; and the third is its entering into com- 
bination with zeolites or similar complex silicates. In 
this form it lends itself, nevertheless, very readily to sub- 
sequent nitrification. It is also known that dry soil will 
absorb gases of various kinds by condensation on the sur- 
face of the particles, analogous to the condensation of 
oxygen on platinum black, and of nitrogen on porous 
copper oxid. 

38. Muntz and Girard's results on the absorption of 
ammonia. — The following data from Miintz and Girard 
show the relative amounts of ammonia absorbed by soil 
and other substances : — 

Ammonia absorbed, per Kilogram op Dry Matter, 
by Different Sorts of Material 

Grams 

Wheat straw 1.70 

Pine sawdust 0.46 

Mossy peat from Holland 8.63 

Powdered peat 11.03 

Siliceous earth 0.66 

Calcareous earth 1.80 

Argillaceous forest soil . 2.24 

Garden soil 5.38 

Peaty soil 6.60 

It will be observed that the highest absorptive power is 
possessed by peat and by soils rich in humus, whereas 
siliceous soil and sawdust both stand low in the list. At- 
tention has been called by Hilgard to the remarkable ab- 
sorptive power, both for ammonia and carbon dioxid, 
possessed by certain highly ferruginous soils of Hawaii, 
which appear to exceed all others in this respect. These 
soils were found to contain as much as 40 per cent of 
ferric oxid accompanied by 3.5 per cent of humus. 



32 FERTILIZERS 

39. The action of gypsum as a preservative of manures. 
— Gypsum, or land plaster, has long been considered one 
of the most important chemical substances for use in the 
preservation of animal manures. Its value is based upon 
its ability to transform the unstable ammonium carbonate 
into ammonium sulfate, whereby its volatilization is 
prevented. This reaction is expressed by the following 
equation : — 

(NH 4 ) 2 C0 3 + CaS0 4 • 2H 2 = (NH 4 ) 2 S0 4 + CaC0 3 4- 2H 2 

ammonium gypsum ammonium calcium water 

carbonate sulfate carbonate 

It requires about 400 parts of water to dissolve 1 part 
of gypsum, although its solubility may be somewhat 
greater in the liquid manure. In order to be effective, 
the manure pile must be kept quite moist in order that the 
solution and transformation, and the consequent fixation, 
may take place promptly and efficiently. 

40. Reasons for using gypsum in excess. — In con- 
sequence of the fact that the reverse reaction to that 
mentioned above is possible, far more than the theoretical 
quantity of gypsum must be used in order to insure the 
fixation of even the chief part of the ammonia. Further- 
more, if the mater'al loses its moisture, some of the am- 
monia of the ammonium sulfate will be changed again into 
ammonium carbonate. Theoretically, 10 to 12 pounds 
of gypsum should be used per ton of dung, but in actual 
practice from 100 to 120 pounds should be employed. 
Another reason for the employment of more than the 
theoretical quantity of gypsum is that potassium carbonate 
and sodium carbonate are present in the urine, which also 
react with gypsum in the same manner as the ammonium 
carbonate. Still another reason for using a generous 



THE DUNG OF FARM ANIMALS 33 

amount of gypsum is that under the most ideal conditions 
for the storage of manure, requiring exclusion of air, con- 
ditions are created favorable to certain anaerobic bacteria, 
which may reduce the sulfate to sulfid. This in turn 
readily reacts with carbonic acid to form calcium carbon- 
ate, with simultaneous liberation of hydrogen sulfid. In 
this way, therefore, some of the gypsum is destroyed and 
its efficiency as a fixer of ammonia is consequently lost. 

41. Gypsum safe to use. — As a manure preservative, 
gypsum possesses the distinct advantage of being a safe 
substance to use under the cows, in contrast to most or 
all of the other materials ; for many of them are likely to 
injure the feet of the cattle unless their use is restricted 
solely to the gutters, or preferably to the manure as it 
leaves the stable. 

42. Gypsum compared with other chemical preserva- 
tives. — It was found by Muntz and Girard, in the course 
of their experiments, that not only gypsum, but sulfate of 
iron, kainit, superphosphate, and calcium carbonate, had 
but slight efficiency as preservatives of dung, a result 
supported by the work of Julie and others. More re- 
cently, however, Severin, in laboratory experiments with 
unsterilized manure, as well as with sterilized manure 
subsequently inoculated with either watery extracts of 
manure or with pure cultures of organisms capable of 
causing ammoniacal fermentation, found that the addi- 
tion of 4 per cent of gypsum to the manure increased the 
decomposition 10 to 20 per cent. It did, however, at the 
same time effect the preservation of the ammoniacal 
nitrogen which had been produced. 

The efficiency of superphosphate as a preservative of 
manure depends primarily upon the gypsum associated 
with it. Its effect may be heightened in some cases by 

D 



34 FERTILIZERS 

the presence of small quantities of sulfuric acid which 
may have been used in excess, or by the presence of small 
amounts of free phosphoric acid. The solubility of the 
phosphoric acid of the acid phosphate is, however, greatly 
lessened when added to the manure, supposedly due to the 
appropriation of the phosphorus by the microorganisms 
present in the mass. 

Further substances which have been employed at various 
times as preservatives of manure are kieserite (crude 
sulfate of magnesia), kainit, sulfuric acid, and moss im- 
pregnated with dilute sulfuric acid. Sulfuric acid has 
also been used for the preservation of liquid manure in 
the cisterns or receptacles in which it is sometimes col- 
lected and stored prior to its application to the land 
The sulfates, and even sulfuric acid, are all subject to the 
same reduction and transformation through the agency 
of anaerobic bacteria as gypsum, on which account they 
have sometimes proved disappointing as preservatives. 

43. Preservation by antiseptics. — In order to stay or 
prevent fermentation in manures, the use of antiseptic 
substances has been proposed. Among these are carbon 
disulfid and soluble fluorids, but they are too expensive 
to justify the attempted saving in the manure. (See in 
a later chapter a discussion of the effect of carbon disulfid 
on soils.) An important consideration in this connection 
is that manures, to be sufficiently effective for the growing 
of early garden crops and for many other purposes, must 
have undergone a certain amount of fermentation of the 
proper kind and under proper control, before they are 
applied to the soil. It must be obvious, therefore, that 
the treatment of the manures with antiseptic substances 
may in the end interfere with the fulfillment of their 
most important function. 



CHAPTER IV 

THE ORGANISMS AND FERMENTATION OF DUNG 

It is but recently that the enormous numbers of micro- 
organisms, and hence the great significances of varying 
conditions upon the changes in animal excrement, have 
been fully recognized. 

44. The number of microorganisms present in cow and 
horse manures. — When the solid excrement is voided, 
it is already swarming with microorganisms. In one gram 
(about one twenty-ninth of an ounce) of cow dung, which 
had been voided but one day, Wiitrich and von Freuden- 
reich found from 7,000,000 to 375,000,000 of organisms. 
The number reported more recently by other investigators 
has ranged from 7,000,000 to 90,000,000. In the dung of 
cows kept in the stall, Guper l found from 1,000,000 to 
120,000,000 of organisms per gram, in contrast to but from 
1,000,000 to 4,000,000 when they were at pasture. 

Better perfected methods show still greater numbers. — 
It has also been claimed that the methods of the investi- 
gators just mentioned were such as to give figures below, 
rather than above, the truth, for by the later and better 
perfected methods, W. Huttemann found in 0.1 c.c. of 
the intestinal content of cattle 1,000,000,000,000 micro- 
organisms. In comparisons of the feces of cattle and horses, 
Stoklasa 2 found in a gram of the former 60,000,000 to 

1 Centralb. f. Bakt., II Abt., 22 (1909), 415. 
2 Fuhling's Landw. Ztg., 56 (1907), 411. 
35 



36 FERTILIZERS 

90,000,000 of microorganisms, and in the same quantity 
of the latter, from 100,000,000 to 150,000,000. 

Microorganisms in human feces. — In human feces, 
Matzuschita 1 found as high as 18,000,000,000 per gram. 
According to Nothnagel, the microorganisms in the feces 
of man often constitute the chief mass of the material, 
and J. Strasburger found that human feces contained 
from 17 to 68 per cent of these organisms. On the dung 
of sheep, List observed lumps consisting of many thou- 
sands of them. Still other investigators substantiate these 
high percentages. 

45. Significance of microorganisms in manure. — It is 
evident from what has preceded that animal excrement 
can no longer be looked upon as a mere storehouse of plant 
food, but as a mass teeming with the most abundant life, 
and capable of undergoing quite different forms of de- 
composition and of yielding widely different products, ac- 
cording to the moisture, temperature, reaction, and the 
kinds and amounts of undigested and metabolic residues 
remaining therein. 

46. Microorganisms in litter. — The number of micro- 
organisms in straw litter has been found to range from 
10,000,000 to 400,000,000 per gram. In peat, used for 
litter, Backhaus and Cronheim have reported from 2,000,- 
000 to 3,250,000 of microorganisms per gram. 

47. Urine, when voided, essentially free from micro- 
organisms. — The urine of healthy animals, when it is 
voided, is either sterile or essentially germ-free. Its in- 
fection, however, results immediately upon being voided, 
and, being a good medium for promoting bacterial growth, 
it is soon teeming with millions of living forms. The ad- 
dition of the liquid to the solid excrement results in a 

1 Archiv f. Hyg., 41 (1901), 210-255. 



ORGANISMS OF DUNG 37 

rapid increase in the organisms, which give rise to the 
formation of ammonia. 

48. The numbers of bacteria decrease gradually. — 
Mixtures consisting of litter and of solid and liquid ex- 
crement are exceedingly rich in living organisms, although 
their numbers finally show a decrease. In manure four- 
teen years old, which had remained without chemical 
treatment and which had shrunk greatly in volume, there 
were found 12,500,000 microorganisms per gram ; whereas 
in identical material, which had been treated with 
kainit and the gypsum residue from the manufacture 
of double superphosphate (" superphosphatgyps "), but 
3,750,000 organisms were found per gram of manure. 

49. The disadvantage of antiseptics. — The employ- 
ment of distinctly antiseptic materials as additions to dung 
would still further lessen the number of microorganisms, 
or destroy some of them completely ; and this fact, as 
mentioned in Section 43, has often been advanced as an 
argument against their use as preservatives of stable 
manure, since the value of the dung for certain purposes 
is enhanced by properly regulated bacterial activity of 
the right sort. To what extent and for how long this 
would hold true for the various antiseptic substances, 
provided the dung were reinoculated with suitable or- 
ganisms, remains to be determined. 

50. Types of microorganisms present in manure. — 
The micrococci and streptococci are generally less numer- 
ous in stable manure than the rod-shaped forms (true 
bacteria) . In moist, well-composted manure, in which the 
conditions for anaerobic fermentation are good, the in- 
testinal streptococci are marked biochemical factors. 
The importance of the micrococci under such conditions 



38 FERTILIZERS 

is certainly small, and Severin 1 observed that the micro- 
cocci in horse manure which was kept under anaerobic 
conditions were soon destroyed. 

In fresh cow dung Backhaus and Cronheim 2 found the 
relation of liquefying to non-liquefying forms of bacteria 
as 1 to 5.5 ; but after maintaining the material for two 
days at 18° C, the proportion was found to be as 1 to 3.5. 
In the fresh dung of other animals, however, the non-spore- 
forming, short-rod forms, belonging normally and chiefly 
to the coli-aerogenes group, were prominent. The fluo- 
rescens and proteus forms are both frequent among the 
liquefying groups. The brown to black fluorescens and 
putidum types are characteristic of manure. These are 
not only of importance in connection with the formation 
of ammonia, but they are also active, together with other 
closely related forms, in effecting denitrification. 

51. Aerobic forms. — Aerobic, spore-forming bacteria 
of the mycoides, subtilis, and mesentericus groups are 
present in great numbers in both litter and solid excrement. 
These are also of importance in the formation of ammonia. 
Included in the foregoing groups are also some of the most 
powerful decomposers of urea, as well as the organisms 
responsible for the development of high temperatures in 
loose, open manure. Among the latter may be men- 
tioned B. subtilis, which continues active in horse manure 
until it reaches a temperature of 71° C. In stable manure 
at 60° to 70° C, Dupont 3 found B. mesentericus ruber, 
but chiefly B. thermophilus grignoni. Neither attacked 
cellulose, but both decomposed the proteins energetically. 
The former attacked starch, sugar, and wood gum, whereas 

1 Oentralb. f. Bakt., II Abt., 1 (1895), 804. 

2 Ber. landw. Inst. Konigsberg, 2 (1898), 23, cited from Lohnis. 

3 Ann. Agron., 27, 1902. 



ORGANISMS OF DUNG 39 

the latter attacked sugar but slightly and starch and wood 
gum not at all. 

52. Spore-forming anaerobic forms. — The spore-form- 
ing anaerobic bacteria may be considered as regular in- 
habitants of the manure pile, although their presence, 
or at least their number, is dependent to a considerable 
extent upon the character of the food consumed by the 
animal producing the manure. Other forms, though 
frequently found in the liquid leachings of manure, are 
not of special agricultural importance. 

53. Actinomycetes. — The actinomycetes are also found 
in stable manure, certain of which are capable of enduring 
high temperatures, and others, such as the " Strahlen- 
pilze " are of importance in connection with the forma- 
tion and decomposition of humous substances. 

54. The yeasts. — Among the yeasts the monilia species 
and Torulacese and even the true saccharomycetes are 
present. 

55. The molds and other organisms. — The molds 
often develop in manure to a serious extent, and at least 
Oidium lactis passes readily through the digestive tract 
uninjured, in which respect it differs widely from the 
yeasts. The molds are powerful destroyers of both ni- 
trogenous and non-nitrogenous constituents of manure. 
This is especially true of very dry horse and sheep manure. 
In the former their growth is the chief cause of the phe- 
nomenon known as " fire-fanging." 

Other organisms which occasionally develop upon fer- 
mented manures, in storage, but which are of relatively 
less agricultural importance, are the myxomycetes. 

56. Animal organisms destroy bacteria. — The pro- 
tozoa may possibly play an equally or even more important 
part in manure than the molds and yeasts, although their 



40 FERTILIZERS 

action is but just beginning to be understood. The recent 
work of Russell and Hutchinson at the Rothamsted ex- 
periment station appears to show that in the soil at least 
amebe and perhaps certain other protozoa feed on living 
bacteria, in some cases to such a serious extent as to greatly 
affect the fertility of the soil. On this account such soils 
may be improved by heating and by the application of 
carbon disulfid, toluene, tricresol, chlorid of lime, and other 
substances which destroy the protozoa and give the bac- 
teria a chance to gain the ascendency. 1 

The idea of the activity of microorganisms in the de- 
composition of stable manure is not new, for special at- 
tention was called to it by Kette in 1865. 2 

57. The effect of heating and of antiseptics on manure. 
— It was shown by Deherain that the addition of chloro- 
form to stable manure very largely, but not completely, 
prevented the formation of carbon dioxid, and that heat- 
ing to a temperature of 85° C. caused the formation of 
methane to cease. 

The elder and younger Schloesing found that stable 
manure heated at temperatures of from 70° to 80° C. 
continued to yield small quantities of hydrogen and carbon 
dioxid ; but less than were produced after heating to tem- 
peratures below 70° C. 

It has been shown by Severin, 3 that in completely 
sterilized manures the formation of ammonia ceased 
entirely, though losses of ammonia by volatilization and 
as a result of the reaction of sulfurous acid on amids, 
were nevertheless possible, due to chemico-physical phe- 
nomena. 

1 Science, 32 (1910), 370. 

2 Die Fermentationstheorie, etc., 2d ed., p. 58 et seq. 

3 Centralb. f. Bakt., II Abt., 1 (1895), 165 and 809. 






ORGANISMS OF DUNG 41 

58. Destructive changes in the non-nitrogenous matter 
of dung. — In the processes of decomposition taking place 
in animal manures, fats and carbohydrates are destroyed 
in large quantities. The loss of these substances is rarely, 
if ever, less than 10 per cent, and is often in excess of 50 
per cent. 

According to Stoklasa, 1 the dry matter of stable manure 
may contain 30 to 40 per cent of cellulose and 20 to 30 
per cent of pentosans. In the dry matter of sheep manure 
and straw litter the amount of pentosans has been found 
by Duhring to be 20 and 29 per cent, respectively, and the 
corresponding percentages of cellulose were found to be 
21 and 38. It seems probable that there may be wide 
variations in these percentages according to the character 
of the food consumed, for in the air-dry dung of sheep 
Weiser and Zaitschek. report 3.6 per cent of pentosans 
and 3.2 per cent of starch ; in the dung of swine they 
found under the same conditions 3.7 per cent of pentosans 
and 3.2 per cent of starch ; and in the air-dry dung of oxen, 
2.6 per cent of pentosans and 10.5 per cent of starch. 

59. Losses not confined to the cellulose. — Certain 
earlier investigators were inclined to the belief that the 
chief loss of carbohydrates during the decomposition of 
animal manures was confined to the cellulose ; yet more 
recent investigations by Miller show that 21.7 per cent of 
the original sugar was lost, also 18.6 per cent of the original 
pentosans, and but 8.7 per cent of the original cellulose. 
It was observed by Sjollema and De Ruyter de Wild, at a 
temperature of 35° C, that under anaerobic conditions 
the pentosans suffered heavy losses ; however, they 
remark that this fact enhances greatly the final value of 
the manure. 

1 FUhling's Landw. Ztg., 56 (1907), 41. 



42 FERTILIZERS 

According to Schloesing, organic matter loses more 
carbon than oxygen, but the hydrogen content remains 
unchanged when organic matter decomposes under ex- 
clusion of air. 

60. Most of the aerobic and anaerobic organisms in 
dung are active. — The majority of the aerobic and 
anaerobic organisms present in horse and cow manures, 
have to do with the decomposition of the carbohydrates. 
Prominent among these are the aerobacter and amylo- 
bacter groups which give rise to volatile and non-volatile 
fatty acids, and to extensive gas production, the latter 
of which represents material losses of vegetable matter. 
B. pimctatum has also been found to be a strong gas 
producer, and B. fluorescens is a powerful liquefier of 
starch. 

61. Diastatic action. — Stable manure contains many 
organisms which exert a diastatic action, among which 
are the molds and the actinomycetes. Certain of the 
bacteria belonging to the mycoides, subtilis, and mesen- 
tericus groups act similarly at certain stages, but the 
yeasts have no diastatic effect whatsoever. 

62. The decomposition of starch. — Starch is transformed 
by B. mesentericus ruber into carbon dioxid, formic acid, 
and valerianic acid ; also sugar into carbon dioxid, acetic 
acid, and butyric acid. B. suaveolens, one of the proteus 
group, transforms starch into sugar, dextrin, alcohol, 
aldehyd, formic acid, acetic acid, and butyric acid. The 
action of the butyric acid bacteria upon starch has been 
found to result in the production of small quantities of 
ethyl alcohol, 35 per cent of butyric acid, and 9 per cent 
of acetic acid. This action, however, depends upon 
varying conditions, and certain members of this group 
may even fail to attack starch at all. 



ORGANISMS OF DUNG 43 

63. The decomposition of pectin. — Among the organ- 
isms effecting the destruction of the pectin of straw and 
manure may be mentioned the aerobic form B. mesen- 
tericus ruber. The organisms chiefly responsible for the 
destruction of pectin are, nevertheless, aided by high 
temperatures and the exclusion of air. 

64. The decomposition of cellulose. — Cellulose ap- 
pears to be capable of destruction by anaerobi organisms, 
denitrifying bacteria, and also by certain aerobic bacteria 
and molds. In manure, however, owing to the lack of oxy- 
gen and nitrates in the interior of the piles, the anaerobic 
bacteria become the chief factors in breaking up th e cellulose. 

It has been shown by the work of Omelianski and of 
Van Senus that certain organisms which are active in the 
formation of butyric acid (the group of B. amylobacter, 
Van Tiegham), which were supposed to destroy cellulose, 
do not attack it, or at least only when it is present in 
amounts not in excess of one per cent. In the latter case 
several of the fatty acids were formed, together with 
traces of higher alcohols and other substances, but the 
gases consisted of C0 2 and H, while CH 4 was entirely 
lacking. This hydrogen fermentation, produced by B. 
fermentationis cellulosce is therefore different from the 
methane fermentation produced by B. methanigenes (Ome- 
lianski), Lehm and Neum, yet both acetic acid and n-bu- 
tyric acid are produced by the latter. Whether the methane 
fermentation or the hydrogen fermentation shall dominate, 
seems to depend upon the existent conditions, but usually 
the methane fermentation is the first to develop. Both 
sets of organisms are, however, present in the intestinal 
tract of domestic animals and are therefore found in the 
dung when it is voided. It appears probable from ex- 
periments with other materials that the methane fer- 



44 ' FERTILIZERS 

mentation may take place more readily in a neutral than 
in an alkaline medium. In this respect the conditions 
are quite the contrary of those favorable to the hydrogen 
fermentation. It is probable also that in open, strongly 
heated manure certain thermophilic decomposers of cellu- 
lose may be present. Furthermore, the particular kind 
and source of the cellulose may likewise be, to a certain 
extent, a factor in determining the nature of the result- 
ing fermentations. 

65. The decomposition of fats and waxes. — In so far 
as concerns the fats and the waxes, it appears probable 
that at least some of them may, under certain circum- 
stances, undergo at least a partial breaking up by an- 
aerobic organisms. Their destruction, which takes place 
readily in the presence of oxygen, is quickly affected 
by exclusion of air. The glycerine which is produced as 
a result of the process is itself quickly destroyed. This 
destruction may be caused by B. boocopricus, an organism 
present in cow dung, and give rise to methyl alcohol, and 
butyric, acetic, and formic acids. 1 In any event, the 
decomposition of the fats and waxes in the manure, when 
it is properly stored, takes place too slowly to have any 
great practical significance. 

66. The decomposition of urea. — One of the first 
changes taking place in stable manure is the breaking up 
of the urea into ammonium carbonate and this finally 
into ammonia, carbon dioxid, and water, as indicated 
below : — 

CO(NH 2 ) 2 = 2 H 2 + (NH 4 ) 2 C0 3 

urea water ammonium carbonate 

(NH 4 ) 2 C0 3 = 2 NH 3 + C0 2 + H 2 

ammonium ammonia carbon water 
carbonate dioxid 

1 O. Emmerling, Ber. d. d. chem. Gesell., 29 (1896), 2726. 



ORGANISMS OF DUNG 45 

This transformation of urea into ammonia is usually prac- 
tically completed in manure piles in from four to five 
days. 

The discoverers of urea, Fourcroy and Vauquelin, 1 
attributed the formation of ammonia to the fermentative 
action of certain slimy substances. That bacteria play a 
prominent part in this change was shown by the investi- 
gations of Alexander Muller 2 and Pasteur. 3 Many later 
investigators have studied the subject, until now the 
number of organisms known to effect the change of urea 
into ammonia is not only very great but also quite varied in 
character, embracing molds and particularly members of 
the various subdivisions of the Coccacese and Bacteriacese. 
Among the latter are embraced the non-spore-producing 
forms such as proteus, coli, and fluorescens, and certain 
of the red and yellow bacteria. Among the most power- 
ful transformers of urea are some of the spore-producing 
bacteria, one of which, Urobacillus pasteuri Miquel, is 
capable of transforming three grams of urea per liter in a 
single hour. Included in the list of the more common forms 
found in stable manure are micrococci, B. pasteuri freuden- 
reichii; also members of the fluorescens, proteus, and coli 
groups. Of these B. pasteuri requires nitrogen from other 
sources than urea, though many of them are fully able to 
depend upon urea for their nitrogen and as a source of 
energy, provided there are also at disposal small quan- 
tities of carbohydrates or salts of organic acids. In the 
case of B. erythrogenes, Sohngen found that, for every 20 
milligrams of carbon supplied in suitable form, 500 milli- 

1 Annal. de Chemie, 31 (1799), 65. 

2 Jour. f. prakt. Chem., 81 (1860), 469 et seq.; (1863), 217 et seq. 
3 Comptes rend. (Paris), 50 (1860), 849-854; Ann. de chemie et de 

phys., (3), 64 (1862), 50-57. 



46 FERTILIZERS 

grams of urea were transformed into ammonia ; and in the 
case of Urobacillus jakschii, Sohng., the relation was that 
of 10 of carbon to 1800 of urea transformed. 

There seems to be a wide diversity of opinion as to the 
role of enzymes in the transformation of urea. 

The mass of bacteria required to transform a given 
quantity of urea is surprisingly small, since Miquel has 
shown that one part by weight of a culture of Urobacillus 
duclauxii was capable of changing 4000 parts of urea into 
ammonia, and Burchard, in experiments with Microc. 
ureoB liquefaciens, found it capable of transforming urea 
into ammonia to the extent of from 180 to 1200 times its 
own weight. Not only is the change rapid, and also great, 
in proportion to the mass of organisms acting, but it is 
likewise often practically absolute. 

67. The decomposition of hippuric acid. — As com- 
pared with urea, hippuric acid is decomposed with much 
difficulty, the resulting products being glycocoll and ben- 
zoic acid, according to the following chemical equation : — 

C 6 H 5 CO • NH • CH 2 COOH + H 2 = 

hippuric acid water 

CH 2 (NH 2 )COOH + C 6 H 5 -COOH 

glycocoll benzoic acid 

The same organisms which actively promote this trans- 
formation also promote the formation of ammonia from 
the glycocoll. ' 

Many of the organisms which produce ammonia from 
urea have the same action upon hippuric acid. Never- 
theless, certain organisms which decompose the one do not 
appear to act strongly on the other. There are, in fact, 
certain specific decomposers of urea, hippuric acid, and of 
uric acid. 



ORGANISMS OF DUNG 47 

68. Changes produced in uric acid. — Under the in- 
fluence of B. arce and of B. fluorescens liquefaciens, both 
urea and ammonia are produced. 1 

It was found by Giglioli that in a case of spontaneous 
infection of a solution of uric acid, only urea and carbon 
dioxid were formed, though Schellmann encountered 
under similar circumstances organisms capable of decom- 
posing both uric acid and urea. 

By the action of Penicillium glaucum uric acid is 
transformed into ammonia, although Aspergillus amidase 
has no effect upon it. Without attempting to go into the 
details of the subject, it suffices to state that uric acid 
very readily yields ammonia under the conditions of fer- 
mentation usually existent in dung heaps. 

69. Ammonification of solid manure and litter. — 
Under the conditions accompanying the usual normal 
fermentation of stable manure, the quantity of ammonia 
actually produced from the nitrogenous substances of 
the solid excrement and of the litter is very small. It 
has been shown repeatedly that a condition most favora- 
ble to the formation of ammonia from such substances is 
exclusion of air. In an experiment by Jentys 2 only one 
•per cent of the nitrogen of solid excrement was changed 
into ammonia in the course of one month under free access 
of air, but, in an artificial atmosphere of nitrogen, 11 per 
cent of nitrogen was changed into ammonia in the same 
period of time. In experiments with a mixture of ma- 
nure and straw, Dietzell 3 found that but 3 per cent of the 
nitrogen was changed into ammonia at the end of six 

1 F. and L. Sestini, Landw. Vers-Sta., 38 (1890), 157-164. 

2 Anzeiger d. Akad. d Wissench., Krakau (1892), 194; cited from 
Lohnis. 

8 Landw. Vers-Sta., 48 (1897), 163 et seq. 



48 FERTILIZERS 

months, in case care was taken to secure good aeration ; 
but that under exclusion of air about 20 per cent of the 
nitrogen had been changed into ammonia. The conditions 
therefore best suited to the formation of ammonia from 
urea are, according to the authorities just mentioned, 
quite the opposite of those essential to the production of 
ammonia from the solid excrement. On this point, how- 
ever, Deherain and Dupont l disagree with the other in- 
vestigators, for they hold that under anaerobic conditions 
the transformation of the albuminoid substances of the 
solid excrement and of the litter into ammonia is very- 
slight, and that it takes place far more readily in the pres- 
ence of air. 

The reasons for the slowness of the formation of am- 
monia in the solid excrement are made perhaps more 
appreciable when one recalls that it is composed, to the 
extent of one-half of its nitrogen content, of the materials 
which have already resisted the action of the digestive fer- 
ments of the stomach or stomachs and of the intestines ; 
and that approximately the other half of the nitrogen is 
in the bacteria and other lower organisms voided with 
the manure. The importance of this point is further 
emphasized by the fact that the organisms mentioned are 
rich in nuclein compounds, and in chitin, all of which 
are highly resistant to decomposition. Furthermore, the 
antienzymes present in the living organisms afford a 
certain resistance to their decomposition and destruction, 
even for a considerable time after their life-functions have 
ceased. 

70. Terms used in discussing the decomposition of 
dung. — Most of the earlier writers have attempted to 

« Ann. Agron., 27 (1901), 401-427; Abs., Zentralb. f. Agr. Chem., 81, 
240. 



ORGANISMS OF DUNG 49 

classiiy the different stages or conditions of the decomposi- 
tion ot animal manures, as fermentation, eremacausis, 
molding, or putrefaction, but no definite lines of demarca- 
tion of these processes, resting upon a scientific basis, has 
been found possible. It is, however, quite customary 
to consider the last two processes as taking place under 
exclusion of air, and by many the last is held to relate 
chiefly to the changes in animal matter, though certain 
writers apply it equally to the changes in the vegetable 
proteins. For the promotion of eremacausis, on the con- 
trary, free access of air is an absolute necessity. The 
production of ammonia was considered by W. Eber : 
as a sure indication of putrefaction, whereas others have 
considered that the formation of skatol, indol, ammonia, 
hydrogen sulfid, or aromatic substances gave such indi- 
cations. Some writers, in agreement with Pasteur, 2 con- 
sider the term applicable only to the decomposition of 
the protein bodies under anaerobic conditions and as 
inapplicable to their decomposition when caused by cer- 
tain aerobic organisms (proteus forms). It has been 
proposed by Hiller 3 that, in place of the previous indefinite 
terms, there should be substituted hydration, reduction, 
and oxidation. It has been pointed out also that it 
depends upon the existing conditions whether the changes 
that take place in a given lot of manure shall receive the 
one or the other designation. As these changes cannot 
be based on definite chemical or biochemical processes, 
owing to the variations in the character of the materials 
at different times and in different parts of a pile of 
manure, there seems to be little gained in attempting 

1 Zeits. f. Fleisch und Milchhyg., / (1891), 118. 

2 Comptes rend. (Paris), 56 (1863), 1189-1194. 

3 Die lehre von der Faulniss (1879), 18-33 and 47. 
£ 



50 FERTILIZERS 

to give to these terms more than their original very 
general significance. One should, therefore, by all means 
avoid their use wherever definite scientific terms can be 
employed. 

71. The nature and cause of the losses occurring in 
manure. — It should be borne in mind that the change of 
urea into ammonia is the result of two stages of transforma- 
tion ; first, to ammonium carbonate, and then to ammonia 
and carbon dioxid. If the reaction could be stopped at 
the end of the first stage by maintaining plenty of mois- 
ture and an excess of carbon dioxid, and if the exclusion 
of the air could also be accomplished, the second stage 
would not readily follow. Under the usual conditions, 
however, not only in urine itself, but also in the usual dung 
heap, the free movement of the air causes the removal 
of the excess of carbon dioxid, thus creating conditions 
favorable to the dissociation of a part of the ammonium 
carbonate. In addition to the direct volatilization of 
ammonia due to the previous loss of carbon dioxid, am- 
monia is also subject to direct oxidation into nitrogen gas 
and water. This change is readily effected by bacterial 
action when the manure pile is open and loose, so that the 
air gains free access. Even though the production of 
carbon dioxid takes place abundantly under such condi- 
tions, it is naturally dissipated into the air, thus rendering 
little aid in preventing the dissociation of the ammonium 
carbonate and the consequent loss of ammonia. 

72. Losses less by fermentation when moist and com- 
pact. — In cases where the manure is kept very moist 
and well trampled from the outset, the aerobic processes 
just described are replaced, after the consumption of the 
small volume of oxygen in the mass, by those of an anaero- 
bic character, giving rise to abundant hydrogen and carbon 



ORGANISMS OF LUNG 51 

dioxid, under conditions which preclude the ready escape 
of ammonia. Following the period of the more rapid 
evolution of hydrogen (which is determined by the con- 
tinued presence of oxygen and the time required to effect 
the destruction of the more readily decomposable carbo- 
hydrates), the evolution of methane increases greatly, 
accompanied also by evolution of carbon dioxid, the for- 
mation of water, and the destruction of much of the cellu- 
lose. The rise of the temperature of the pile, due to the 
changes induced by the utilization of the oxygen by the 
aerobic bacteria present in the mass, is soon followed by a 
material drop in the temperature. 

73. Losses increased by bacteria from intestinal tract. 

— Aside from the changes which have been mentioned, 
still others initiated by bacteria from the intestinal tract 
(among which is B. coli communis), aided by micro- 
organisms present in the air, bring about the destruction 
of the proteins and effect their transformation into amids, 
amino-acids, and eventually ammonia. These changes 
are accompanied by the formation of various fatty acids, 
chief among which is butyric acid. 

74. Losses smaller in the later stages of decomposition. 

— It is a notable fact that in the later stages of the fer- 
mentation of stable manure, only small direct losses of 
ammonia take place. This is readily understood, in view 
of the enormous numbers of bacteria and other organisms 
involved in the many transformations taking place in the 
nitrogenous and non-nitrogenous portions of the litter 
and manure ; for considerable quantities of the ammonia 
are built up into the structure of the organisms themselves, 
whereby it becomes less subject to material loss, though 
depreciating greatly its immediate manurial efficiency. 
In other words, the ammonia becomes transformed, by 



52 FERTILIZERS 

this process, into combinations similar to those existing 
in the soil humus. 

As a result not only of the fermentation of the carbohy- 
drates, but also of the proteins of the dung and litter, 
organic acids are formed, which are neutralized by the 
ammonia. Carbonates of the alkalies are likewise pro- 
duced in the course of the destructive processes, and these, 
by their solvent action upon the dead bacteria, give rise 
to the dark liquors which are characteristic of the leachings 
of old dung heaps. 

Least when only the ammoniacal stage has been reached. — 
The best results are to be expected from manure which 
has passed only to the second or ammoniacal stage, rather 
than from that which has reached the most advanced stage 
of decomposition, for the ammonia is then ready to undergo 
immediate nitrification as soon as the manure is brought 
into the soil. Furthermore, at this stage the vegetable 
matter is so far destroyed as not to have a serious effect 
upon plants or to greatly promote the destruction of ni- 
trates in the soil. At the same time, also, there is much 
material still present in forms suitable for promoting the 
growth of such organisms as assimilate nitrogen directly 
from the air, which, in their turn, add to the store of nitro- 
gen in the soil. 

75. Fresh manure lacks immediate effectiveness. — 
The idea has been handed down from early in the last cen- 
tury that fresh stable manure can be employed with the 
best results only when considerable time elapses between 
its application and the date of planting. The effect of 
fresh manure is said to be worse in light soils than in 
those which are heavy. Many writers insist that the straw 
in the litter should be quite well broken up by the processes 
of decomposition before its application. The time nee- 



ORGANISMS OF DUNG 53 

essary for the accomplishment of this varies greatly with 
the location and the season. It would naturally take place 
more quickly in a moist, warm climate than in one which 
is dry and cold. In the winter these desired changes may 
require a period ranging from eight to twenty weeks. 

76. The great necessity of moisture in heaps of solid 
manure. — From what has preceded, it appears that the 
best condition for the preservation of solid manure is that 
it should be kept moist by the liquid excrement, or, if this 
is insufficient, by additions of water. This is well recog- 
nized in France and other European countries where the 
manure is kept under cover, and is so situated that any 
seepage from it may be pumped back again upon the top 
of the pile. If in such cases a considerable loss of liquid 
results by evaporation, water is added to replace it. For 
a similar reason it is a more or less common practice among 
gardeners who buy large quantities of stable manure, to 
be stored in piles in the field, to have the tops of the piles 
incline towards the center so that they w r ill catch rather 
than shed the rainfall. This prevents too rapid changes 
and the losses due to the presence of oxygen and the con- 
sequent rapid multiplication of undesirable classes of 
microorganisms. 

77. The preservation of the liquid manure. — It is 
important in the preservation of the liquid manure that it 
be subjected to both the chemical and physical absorbent 
action of the litter. If the liquid manure is collected in a 
cistern or reservoir by itself, the receptacle should be 
closed tightly in order to prevent the passage of air cur- 
rents over it, for the ideal condition for the preservation 
of liquid manure is to have it covered with a layer of carbon 
dioxid gas which prevents the rapid dissociation of the 
ammonium carbonate. It is probably safe to assert that 



54 FERTILIZERS 

even if the greatest care is taken to preserve the liquid 
manure as completely as possible by itself, there is never- 
theless more loss than if it is mixed with the solid manure 
and is then spread on the soil at once or at frequent 
intervals. 



CHAPTER V 

THE PRACTICAL UTILIZATION OF MANURES 

The important feature in connection with manures is 
that what has been learned in relation to their fermentation 
and conservation be applied in a practical way, and these 
matters will now be discussed in detail. 

78. Storage versus direct application of manure. — 
It is still a much discussed subject whether stable manure 
should be allowed to lie in the stable or under a shed until 
needed, or whether it should be hauled to the field and 
spread as rapidly as it is produced. At all events, if the 
choice lies between its remaining for several days or weeks 
in a loose heap before it can be spread, especially in the 
summer time, or its being trampled down and preserved 
at once, together with the liquid manure, no doubt the 
latter is by far the better method of storage. If, however, 
the manure can be hauled out daily and incorporated with 
the soil at once, the greatest possible conservation of the 
nitrogen will result. If the manure is spread broadcast 
in the field just prior to a rain, the soluble portion will be 
carried into the soil, and the loss of nitrogen will then be 
reduced nearly to a minimum. 

The danger of the loss of manure on ordinary slopes, 
under usual conditions, by surface leaching, is not great 
unless the soil is exceptionally impervious and the rainfall 
unusually heavy and long continued . Applications should , 
however, never be made on such locations when the land 
is frozen deeply or when it is covered with a thick bed of ice. 

55 



56 FERTILIZERS 

When the ground is fairly level and is not frozen mate- 
rially, even if covered with light or moderate amounts of 
snow, the dung of horses and cattle can be applied with 
much safety. 

There is much to be said from a practical business 
standpoint in favor of the direct application of such 
manures to the land, even aside from the prevention of 
manurial losses. If they are not applied as produced, the 
farmer finds himself seriously handicapped in the spring by 
the necessity of hauling them out when the planting should 
be in progress, and thus a series of delays and consequent 
losses often follow throughout the year. 

79. Immediate incorporation of manure with the soil. 
— From the standpoint of the conservation of the am- 
monia, probably no more rational advice could be given 
than that by Deherain, to the effect that a shallow furrow 
should be turned over the manure, if possible, as rapidly 
as it is applied to the land. In view, however, of the great 
cost of labor in the United States, a second plowing of the 
land, such as would be required by this method, would 
hardly make it an economical proposition. On light soils, 
it would be more advisable to turn the manure under in 
one operation, to the usual depth of plowing, and on heavy 
soils to spread it after plowing and then incorporate it 
with the soil by immediate harrowing. 

80. Losses occurring in heaps in the field and if broad- 
casted. — If well fermented manure must be hauled to the 
field a considerable time before it can be incorporated with 
the soil, either by plowing or harrowing, the ammonia 
will be best conserved if it is placed in large piles. In case 
it is left in small heaps, as was formerly the common prac- 
tice in New England, until it is convenient to spread it, 
the sun dries out the liquid, the winds carry away the car- 



THE PRACTICAL UTILIZATION OF MANURES 57 

bon dioxid, the dissociation of the ammonium carbonate 
is thus facilitated, and the ammonia is rapidly volatilized. 
One of the most serious wastes which can occur is from 
leaving such manure spread for a long time upon the surface 
of the ground in pleasant weather, exposed to the sun and 
wind. Under such conditions, great losses of ammonia 
are inevitable. As compared with the losses which may 
result in this manner, those due to the usual application 
of fresh manure directly to the soil are probably very small. 

81. The time to spread manure on fields. — If on any 
account partially fermented manure must be allowed to lie 
on the surface of fields for some time before it can be in- 
corporated with the soil, its application should preferably 
take place just prior to or during a fall of rain, or upon a 
light, fresh fall of snow, in order that the ammonium 
carbonate may be carried directly into the soil, for, as 
explained previously, the soil readily absorbs and holds 
ammonia, excepting under conditions not commonly met 
with in agricultural practice. 

82. Certain vegetable substances aid denilrification in 
manures. — The scientific study of the management of 
animal manures was taken up a few years ago with re- 
newed interest as a result of inducements offered by the 
Deutsche Landwirtschafts Gesellschaft (German Agricul- 
tural Society). In the course of this work it was found by 
several German investigators that the solid excrement of 
certain farm animals was worse than useless, for, by its 
incorporation with the soil, crops were lessened rather than 
increased. This led to a study of the action of straw in 
order to learn if it, or solely the solid excrement with which 
it was commonly associated, was responsible for this 
effect. As a result, it was found that straw also, when 
incorporated with the soil, often lessened rather than in- 



58 FERTILIZERS 

creased the yields. The further pursuit of the problem 
led to the discovery that the ill effects resulting from the 
employment of the straw and the fresh excrement of farm 
animals, in large quantities, were caused chiefly by the 
destruction of the nitrates within the soil, whereby a large 
portion of their nitrogen was liberated from the soil as 
free nitrogen gas, and in consequence the plants suffered 
from nitrogen hunger. It was also believed for a time that 
this ill effect of straw was because of its being a possible 
carrier of the denitrifying organisms and that its malign 
influence was directly attributable thereto. 

83. Losses by denitrification less serious if used moder- 
ately. — As a protest against the foregoing results and 
against the conclusions drawn therefrom, attention should 
be called to the common experience of farmers and also 
to the long-continued experiments with animal manures 
at Rothamsted, England, from which their immediate, as 
well as their long-enduring, effects are evident. Further- 
more, at Rothamsted the yields were greatly increased by 
supplementing the barn-yard manure with nitrates, from 
which it is evident that the latter were probably not 
wholly destroyed. In this connection much credit is due 
to Deherain for pointing out the fact that in many of the 
German experiments, which were mostly conducted in 
pots, boxes, or small soil receptacles of various kinds, the 
ratio of the manure and straw to the soil was far greater 
than is customary in actual field practice, where, except- 
ing in truck farming, only from four to ten cords of manure 
per acre are usually employed. It was also pointed out 
by Deherain that with all of the other conditions uniform, 
starch and other carbohydrates, including the pentosans, 
became the determining factors in causing the destruction 
of nitrates. In fact, it was shown conclusively that by the 



THE PRACTICAL UTILIZATION OF MANURES 59 

use of unduly large amounts of straw and of solid manure, 
the soil became well supplied with the carbohydrate foods 
required by the denitrifying organisms, whereby their 
multiplication in the soil and their activity as destroyers 
of nitrates were greatly increased. 

From what has preceded it appears that the greatest econ- 
omy in the use of coarse animal manures in the field is prob- 
ably effected by the use of small or moderate applications, 
rather than by large ones. These observations also show 
another reason why partially rotted manure is much su- 
perior, for inducing quick growth, to comparatively fresh 
manure ; for the former is much more heavily charged with 
food for the denitrifying organisms than that which has 
undergone a greater amount of fermentation. 

84. Other factors affecting losses by denitrification. — 
It is obvious, also, that the manure of animals which have 
digested their food the most thoroughly is less likely to 
induce denitrification than that which is less completely 
acted upon by the digestive agents. The effect of manure 
in inducing denitrification is obviously determined, to some 
extent, by the character of the food consumed. 

It has been shown experimentally that if a given amount 
of vegetable matter is introduced into the soil in a coarse 
condition and in a manner which does not admit of a com- 
plete admixture with the soil, it is less serious by way of 
inducing the destruction of nitrates than when the same 
material is ground and carefully mixed with the entire 
mass of the soil. The explanation is that in the latter 
case food is present at every point in the soil for the denitri- 
fying organisms, which insures their general distribution 
and consequent greater destruction of nitrates than would 
be possible if they were only distributed here and there 
wherever the coarse portions of vegetable matter happened 



60 ' FERTILIZERS 

to be present. Herein is found a partial explanation of 
the alleged better results secured on certain soils by plow- 
ing under the manure than by harrowing it into the soil 
in a thorough manner. 

85. The lasting effect of stable manure. — Notwith- 
standing all that has been said about the immediate action 
of large quantities of litter and of solid manure by way of 
favoring denitrification, their beneficial after effects in the 
soil are of long duration, as the Rothamsted experiments 
have fully demonstrated. In this connection Director 
Hall of the Rothamsted station gives the results on grass 
where stable manure was applied at the rate of 14 tons per 
acre per annum for eight successive years (1856-1863), 
the land then being left in grass without manure or fer- 
tilizer for forty years. These results are compared with 
those secured on a similar field to which no manure was 
applied. The greatest increase over the unmanured area 
was in 1865, two years after the last application was made. 
The gain in that year amounted to 120 per cent. In the 
decade from 1866 to 1875, and for the three decades there- 
after, the average increase in the produce, due to previous 
applications of manure, was 57, 24, 6, and 15 per cent, re- 
spectively. 

In connection with the Rothamsted barley experiments, 
one plat received 14 tons per acre of stable manure for 
each of the twenty years from 1852 to 1871 ; a second plat 
has received the same amount per annum continuously; 
and a third has had none. The results show that the 
yields are still more than twice as great on the plat which 
received the manure for the twenty years as where none 
hag been applied. The yields are now, nevertheless, only 
about 40 per cent of what they are where the application 
of manure has been continuous. Attention is called, 



THE PRACTICAL UTILIZATION OF MANURES 61 

however, by Hall to the fact that such a long duration of 
the effect of residues of farm-yard manure would not be 
perceptible in ordinary farm practice, and that they only 
become apparent when the soils are cropped to a state 
of exhaustion which is most unusual. 

86. Manure profitably supplemented by chemical 
fertilizers. — Where farm-yard manure commands a high 
price, or where the cost of hauling is great, it is usually 
better economy to employ only moderate amounts and to 
supplement it with chemicals, than to place entire de- 
pendence upon it. This is well shown by experiments 
at Rothamsted in which the use of 200 pounds of nitro- 
gen in stable manure resulted in a yield of but 27.2 tons 
of mangel wurzels, as compared with a yield of 33 tons 
where but 86 pounds of nitrogen were applied in nitrate 
of soda, which was properly supplemented with potash 
and phosphoric acid. The farm-yard manure used with 
the same amount of nitrate of soda gave a yield of 41.4 
tons, and when further supplemented by potash and phos- 
phoric acid, the yield was only increased about 0.1 ton. 
Had the precaution not been taken to add potash salts 
with the manure and nitrate of soda, there would have 
been reason for concluding that the differences in yields 
were possibly attributable to the soda of the nitrate of 
soda, rather than to the nitrogen. This is evident from 
the experiments conducted at the Rhode Island station, 
in which it was found that the yield of mangel wurzels 
could be doubled by the employment of either sodium 
carbonate or sodium chlorid, even when as much as 330 
pounds per acre of muriate of potash, or its equivalent 
of potassium carbonate, had already been used in the 
manures. In this case, however, it was found to have 
been probably due not alone to possible liberation of pot- 



62 FERTILIZERS 

ash from the soil, but to direct substitution of the soda, for 
at least a part of the potash, in connection with the require- 
ments for bases, or in one or more of the physiological 
functions of the plants. 

87. Factors governing use of manure and chemicals. — 
If, in the operations of the farm, the products can be fed 
at a good profit, so that the farm-yard manure can be 
secured as a costless by-product in sufficient quantities to 
meet the entire manurial needs of the farm, it should be 
used as generally as possible even for the top-dressing of 
grass land. It may even be used in connection with the 
potato crop, under favorable conditions, provided the 
" seed " tubers are properly treated with formalin or 
corrosive sublimate solution for the prevention of scab. 

If the supply of manure is small, the potato crop is one 
for which chemical fertilizers can usually be substituted 
to good advantage, particularly as the fertilizers are more 
likely to produce a crop free from scab and from insect 
injury. 

88. The use of coarse manures. — If the manure is 
coarse, by virtue of being mixed with bulky litter, it is 
poorly adapted to the top-dressing of grass land. For such 
purposes the employment of fresh manure during the late 
autumn and in the winter months may be permissible, 
if there is no better use for it elsewhere. For spring top- 
dressing the manure should by all means be fine, and, if 
applied at such times as to avoid excessive losses of am- 
monia, it may be well rotted. The application of coarse 
manure may not only smother the grass, but there is also 
danger that some of the material will finally be raked up 
with the hay. On account of the fact that the soluble 
ingredients of manures diffuse but little laterally in the 
soil, it is important that top-dressings be very evenly 



THE PRACTICAL UTILIZATION OF MANURE 63 

distributed, but this is difficult of accomplishment if the 
manure is excessively coarse. 

If the manure is coarse and it is used on light soils, it 
may be plowed under, but if it is fine and it is to be applied 
to rather heavy soils, it is usually considered preferable to 
harrow it into the soil. As a general rule, farm-yard 
manure should be applied to hoed crops. 

89. Reason for even spreading of manure. — The 
failure of fertilizers and manures to move laterally in the 
soil has been abundantly observed at Rothamsted, and it 
may be readily seen where a soluble chemical fertilizer is 
applied to grass land, for even after abundant rains the 
effect is often hardly visible for more than an inch or two 
beyond the limit to which it has been spread. 

90. Manure favors the disintegration of old soil. — 
In breaking up old grass fields, the soil of which is in poor 
tilth, it is advisable to spread a small amount of stable 
manure broadcast before plowing, since it will serve as an 
efficient aid in hastening the decomposition of the turf, 
which is one of the first and most important steps in the 
line of effective soil improvement. This may be followed, 
if required, by an application of lime, which should be 
most thoroughly harrowed into the soil. Support for 
this proposed method of using stable manure is afforded 
by the recent experiments of A. Koch, 1 who inoculated 
mixtures of soil and cellulose, with ordinary soil, compost, 
barn-yard manure, and sewer slime. The average amount 
of cellulose consumed in six months amounted to 1.2 
grams when soil was employed, to 3.85 grams with com- 
post, to 10.35 grams with farm-yard manure, and to 1.85 
grams with sewer slime. The average amount of nitrogen 
finally present in each, in milligrams per 100 grams of 

1 Abs. E.S.R. 27 (1910), 429. 



64 ' FERTILIZERS 

dry soil, was 10.73 with soil, 92.05 with compost, 117.27 
with stable manure, and 87.15 with sewer slime. From 
this it will be seen that the organisms present in the stable 
manure rendered possible the use of the cellulose as a 
source of energy in connection with the fixation of atmos- 
pheric nitrogen. Thus the introduction of stable manure 
into the soil, even in small quantities, may not only aid 
the decomposition of the excess of grass roots, whereby 
the general tilth is improved, but it may also aid materi- 
ally by encouraging the growth of those organisms which 
assimilate atmospheric nitrogen, quite independent of the 
growth of legumes. 



CHAPTER VI 



SEA-WEEDS 



Under the name of sea-weeds are sometimes grouped not 
only the marine algse, but occasionally other marine plants, 
one of the most 
common of 
which, on cer- 
tain coasts, is 
the eel-grass, 
or grass-wrack 
(Zostera ma- 
rina), which be- 
longs to the 
Naidacse or 
Pond- we e d 
family. 

The number 
of marine 
plants which 
are not algae is 
very small on 
the New Eng- 
land coast, and 
is said to hardly 
exceed half a 
dozen. 

91. The value of sea-weed known to the ancients. — 
The use of sea-weed as a manure was already well known to 
f 65 




Fig. 2. — Sea-weed for Fertilizing. 
Ribbon-weed, kelp, tangle {Lamina ria saccharina). 



66 



FERTILIZERS 



the early Romans, as is shown by the writings of Palla- 
dium, who stated that after washing with fresh water, it, 
with other substances, can take the place of manure. 
Sea-weed has long been used for manurial purposes in the 
islands of Thanet and Jersey ; also in the Hebrides, Scot- 
land, England, Ireland, Wales, Sweden, and elsewhere. 

Percentage Composition of Sea-weeds 1 









Phos- 










Water 


Nitro- 


phoric 


Pot- 


Lime 


Mag- 






gen 


Acid 


ash 




nesia 


Ribbon-weed, kelp, or tan- 














gle {Laminaria saccha- 
















SS.O 


0.17 


0.05 


0.16 


0.38 


0.17 


Broad ribbon-weed, broad- 














leafed kelp, devil's 














apron, or tangle (Lami- 














naria digitata) 2 


87.5 


0.23 


0.06 


0.31 


0.41 


0.22 


Dulse, or dillisk (Rhody- 














menia palmata) 2 . . . 


86.3 


0.37 


0.09 


1.07 


0.46 


0.09 


Round-stalked rock-weed 














(Ascophyllum (Fucus) 
















77.3 


0.24 


0.08 


0.64 


0.48 


0.35 


Flat-stalked rock-weed 














(Fucus vesiculosus) 2 . 


76.6 


0.38 


0.12 


0.65 


0.45 


0.31 


Phyllophora membranifolia 2 


66.2 


1.0S 


0.14 


0.96 


5.11 « 


0.69 


Irish, or Carrageen, moss 














(Chondrus crispus) 2 . 


76.0 


0.57 


0.13 


1.02 


0.49 


0.33 


Cladoslephus verlicillatus 3 . 


71.2 


0.45 


0.22 


1.42 


0.87 


0.36 


Polyides rotundus 3 . . . 


58.5 


0.70 


0.16 


1.45 


0.37 


0.46 


Ahnfeldtia plicata 3 . . . 


59.0 


1.35 


0.25 


0.59 


0.98 


0.29 


Eel-grass, or grass-wrack 














(Zostera marina) 2 


81.2 


0.35 


0.07 


0.32 


0.51 


0.32 



1 A tabulation of analyses of sea-weeds by a number of analysts, in 
several different countries, all of which are reduced to a dry basis, may 
be found in Bulletin No. 21, Rhode Island agricultural experiment 
station, pp. 34-36. 

2 Average of samples taken in January, March, and September. 
' 3 Samples taken in September. 

4 More or less small shells adhered to the plants, which explains the 
exceptionally high lime content. 



SEA-WEEDS 



C7 



92. Chemical composition of sea-weeds. — Most of 
the earlier analyses of sea-weed were of the ash rather than 
of the entire plant. In many cases either the moisture con- 
tent of the original 
plant was not given, or 
no distinction was made 
between " pure " and 
" crude " ash, on which 
account it is impossible 
to calculate the com- 
position of the plants 
from which the ash was 
secured. On this ac- 
count the number of 
analyses of sea-weeds 
in their natural condi- 
tion is small, a fact that 
is regrettable for the 
reason that most of the 
sea-weeds used for 
manurial purposes, at 
least in the United 
States, are applied to 
the soil without drying, 
composting, or burning. 

The analyses on the 
opposite page by 
Wheeler and Hartwell 
show the composition of several different varieties, fol- 
lowing the rinsing off of the salt water and the removal 
of the superficial moisture. 

93. The composition varies at different seasons. — 
With but few exceptions, samples of sea-weed brought up 




Fig. 3. — Sea-weed for Fertilizing. 

Broad ribbon-weed, broad-leafed kelp, 

devil's apron, tangle (Latninaria digitata). 



68 FERTILIZERS 

by the tide and collected on the shore in January and 
March were found to be richer in nitrogen, potash, and 
phosphoric acid than those collected in September. This 
may possibly be accounted for in part by previous partial 
drying in the warmer month of September, on account of 




Fig. 4. — Sea-weed for Fertilizing. 
Dulse, dillisk (Rhodymenia palmata). 

which the specimens suffered some loss by leaching either 
in the sea-water or by falling rain. 

94. Sea-weeds of chief importance in New England. — 
Among the sea-weeds which are most abundant on the 
New England coast, the Irish moss is one of the best. 
This is followed in value by the dulse (dillisk), the flat- 
stalked rock-weed, the round-stalked rock-weed, and 
finally by the kelps. The other varieties of the algse 



SEA-WEEDS 



69 



mentioned are found in such small quantities as to be of 
only minor agricultural importance. 

95. The value of eel-grass. — The eel-grass, unlike 
the algse, decomposes very slowly, and hence is not suitable 
for the top-dressing of meadows. For the same reason 




Fig. 5. — Sea-weed fob Fertilizing. 

Round-stalked rock-weed (Ascophyllum, or Fucus, 

nodosum). 

it is less valuable when turned under as a manure, and it 
may even act injuriously in such cases if used in large 
quantities in a dry season. The best method of using it 
is as litter for swine or other farm animals. 

96. Value limited by distance of land. — The usual 
limit of distance to which sea-weed has been carted inland 
in the United States is from eight to ten miles, but even 



70 FERTILIZERS 

then in some cases it is not profitable, if the teams and 
laborers can be employed economically for other pur- 
poses. 

97. Practical utilization. — Such sea-weeds as decom- 
pose most readily can be used for the autumn and winter 
top-dressing of grass lands, provided they are not em- 
ployed in such quantities as to smother the grass. As a 
rule, however, they "can be used to the best advantage on 
land which is about to be plowed. Sea-weeds are generally 
considered preferable to stable manure in so far as con- 
cerns their effect upon the smoothness of the potato crop ; 
but in regard to the cooking qualities of the tubers, un- 
favorable results from their use have been reported. It 
has in fact been shown by experiments at the agricultural 
experiment station in Rhode Island that the difference in 
the smoothness of the tubers is due to the alkaline effect 
of the farm-yard manure on the one hand, which creates 
conditions favorable to the development of potato scab, 
whereas common salt and other chlorids, such as are 
associated with sea-weed, have the opposite tendency. 
Furthermore, sea-weed itself would not exert an immediate 
alkaline effect, like farm-yard manures. 

98. Effect on the quality of certain crops. — As con- 
cerns the effect of sea- weeds on the cooking quality and 
the composition of the potato, it must be borne in mind 
that if not leached they carry common salt, and that 
Schultz (of Lupitz), Salfeld, and other German experimen- 
ters have shown conclusively that the application of chlo- 
rids, just before planting the potato crop, results in a 
depression of the starch cont'ent of the tubers, increasing 
at the same time their nitrogen content, and causing the 
frequent development of a disagreeable soapy taste. 

On account of the adhering sea- water, sea- weed may also 



SEA-WEEDS 71 

be injurious to hops, to the burning quality of tobacco, 
and it may depress the sugar content of beets. It is be- 
cause of this well-recognized action that it has become 
customary, in certain countries, to allow the sea-weed to 
be leached by rains before carting it upon the land used for 
farming purposes. The same result is often accomplished 
in part on the coast of New England, without thought of 




Fig. 6. — Sea-weed for Fertilizing. 
Flat-stalked rock-weed (Fucus vesiculosus) . 

this feature, by the practice in times of storm of carting 
the sea-weed into piles a short distance from the shore, 
until a favorable opportunity is presented for hauling it 
away. This possible danger from the use of sea-weed 
may be very largely or wholly obviated by applying it 
either the autumn or winter previous to the time when 
crops subject to such injury are to be grown. 

99. Sea-weed quick in its action. — Owing to its 
undergoing ready decomposition, sea-weed is to be classed 



72 FERTILIZERS 

as a quickly acting manure, which exerts its chief effects 
the first season. 

100. Sea-weed compared with farm-yard manure. — 
In the Western Islands, a load of farm-yard manure is 
considered as being equal to two and one-half loads of 
fresh sea-weed, or to one and three-fourths loads of sea- 
weed which has lain in a pile for two months. 

101. Sea-weed not a well-balanced manure. — It is 
well recognized that sea-weed is not a well-balanced ma- 
nure for all soils and crops, and that to supply the needed 
amounts of phosphoric acid in sea-weed, in all cases, 
would result in a frequent waste of potash or nitrogen, or 
of both. On this account, sea-weed should be supple- 
mented, especially where the cost of hauling is great, by 
bone meal, basic slag meal, acid phosphate, or other phos- 
phatic fertilizers. 

102. Sea-weed as affecting the need of liming. — In 
case sea-weeds are used frequently and they carry, attached 
to them, a considerable quantity of the shells of mollusks, 
these will supply more or less carbonate of lime, and 
thus render liming unnecessary, whereas if they are very 
free from shells, they may ultimately have the opposite 
effect. 

103. Freedom from weed seeds a great advantage. — 
A strong point in favor of sea-weeds, as compared with 
farm-yard manure, is their freedom from weed seeds. It 
is stated that on this account farmers in certain sections 
apply the farm-yard manure to their grass lands and re- 
serve the sea-weed for their hoed crops. It is indeed 
related by M. Herve Mangon l that on an island off the 
coast of France (Noirmoutiers) cattle are kept in large 
numbers, but the dung is dried and used as fuel ; the ashes 

1 Comptes rend., 49 (Paris, 1859), 322. 



SEA-WEEDS 



73 



of the dung and the native sea-weeds being the only ma- 
nures used there for centuries. 

104. Composting sea-weeds. — The composting of sea- 
weeds, as is frequently recommended in Europe, especially 
in Sweden and other cold countries, is not usually con- 
sidered economical in the United States on account of 
the cost of labor involved in handling them. Sea-weeds 




Fig. 7. — Sea-weed for Fertilizing. 
Irish, or Carrageen, moss {Chondrus crispus). 



are composted to a considerable extent on the coast of 
Brittany, France ; and Turner tells of their being com- 
posted in Devonshire, England, where they are often piled 
in layers, each from 6 to 8 inches deep, with a quantity 
of lime scattered between. The pile is then turned over 
occasionally, and at the end of from two to three months, 
when well rotted, it is ready for use. Sea-weeds are also 
often composted with stable manure, but whatever the 
method followed it is a wise plan to keep the pile covered 



74 FERTILIZERS 

with at least a thin layer of moist soil, in order to prevent 
the possible loss of ammonia. 

105. Size and rapidity of growth of sea-weeds. — A 
good idea of the rapidity of the growth of sea-weed is 
furnished by an instance in Scotland where a rock, which 
was uncovered only during the lowest tides, was chiseled 
smooth in November and was thickly covered by the 
following May with sea-weeds ranging in length from 2 
to 6 feet. The growth of certain of the giant sea-weeds 
of the Pacific coast and elsewhere must be exceedingly 
rapid, for some of these plants are said to be annuals 
propagated from spores ; and specimens of Nereocystis 
luetkeana (Mertens) Postels and Ruprecht, for example, 
have been observed, that were over 300 feet long. Further- 
more, McFarland (Fertilizer Resources of the United 
States, Senate Document No. 190, 62d Congress, 2d 
Session) also reports them 100 feet in length. 

The giant kelp (Macrocystis purifera, Turner) (Agardh.) 
is said to be attached to the bottom by a holdfast which 
reaches three feet in diameter. The stem at first branches 
equally, but the later divisions grow to unequal lengths, 
some of which often extend to from 300 to 700 feet ; and 
in exceptional instances the total length of some of these 
plants has been said to be fully 1500 feet. 



CHAPTER VII 

GUANOS 

The name "guano" is derived from the Spanish word 
" Huano " which means dung. Its use for agricultural 
purposes dates, according to Garcilaso de la Vega, from 
the twelfth century, and in the year 1154 it is known to 
have been carried to Edrisi in Arabia. The European 
travelers Feuille, in 1710; Frezier, in 1713; and Ullao, 
in 1740, all speak of the great value of guano as a manure. 

106. Experimental trials of guano. — In 1804 Alexander 
von Humboldt took some guano to Germany, where it 
was examined chemically. At the instance of Sir John B. 
Lawes experiments were conducted with it by General 
Beatson at St. Helena in connection with the growth of 
potatoes, with most beneficial results. In 1824 Skinner 
of Baltimore received two casks of guano which served 
to demonstrate its value in the United States. 

107. Commercial introduction into Europe. — The first 
attempts at the introduction of guano into Europe, in a 
commercial way, in 1835 resulted in failure ; nevertheless 
in 1840 Quiros Allier & Co. of Lima made a shipment to 
Liverpool which was given a trial by the Royal Agricul- 
tural Society. The results were so good that the company 
made a six-year contract with the Peruvian government 
for the exclusive export of guano. The contract was 
signed on December 17, 1840, and in March of the follow- 
ing year the shipment was begun. It was continued 

75 



76 FERTILIZERS 

with such success that by October of that year twenty- 
three ship-loads had been sent to Europe. One of these 
vessels carried to Germany the first consignments made 
to that country. This was followed by a vessel load in 
February, 1842. 

Reports of the high prices received for the guano in 
England soon caused the Peruvian government to with- 
draw its contract and to enter into more favorable four- 
year contracts with several firms. 

108. The general nature of guano. — Guano is pop- 
ularly supposed to consist exclusively of the excrement of 
sea-fowl which roost upon the islands or mainlands in 
great numbers, especially at night. Other common con- 
stituents are the feathers, bones, and bodies of the birds 
themselves, and the excrement and remains of large 
marine animals, which not only visit the shores frequently, 
but often die there by thousands, as may be seen by their 
skeletons scattered over the guano. 

109. The chemical composition of guanos. — The 
frequent, penetrating odor of guano is due to the presence 
of ammonia and of certain organic acids. Guano consists 
chiefly of uric acid, oxalic acid, fatty acids, resinous 
matter, guanin, organic matter rich in sulfur, phos- 

Per Cent 

Total nitrogen . 16.34 

Ammonia already formed 14.08 

Tricaleium phosphate 32.30 

Potash 1.94 

Lime 5.11 

Magnesia 3.69 

Sulfuric aeid 0.62 

Chlorin 1.04 

Soda 0.54 

Iron oxid 0.18 

Sand and silica 1.45 

Water 17.13 



GUANOS 77 

phoric acid united with lime and magnesia, ammonium 
sulfate, potassium sulfate, sodium chlorid, potassium 
chlorid, silicic acid, and sand. The table on the opposite 
page is an analysis of guano by Karmrodt. 

Guano differs widely from the dung of domestic fowl 
in its greater percentages of nitrogen and of phosphoric 
acid. This is caused by the fact that the sea-birds live 
exclusively on .fish, which are rich in nitrogen and in 
phosphate of lime, whereas the food of domestic birds con- 
sists chiefly of cereals, which are relatively poor in these 
ingredients. 

110. Chemical composition affected by climatic con- 
ditions. — The great variations in the composition of 
guano are due to the widely varying climatic conditions 
to which it is exposed. In a practically rainless climate 
the naturally moist excrement dries quickly without under- 
going material decomposition, in consequence of which 
its natural content of nitrogen and of phosphoric acid is 
still further increased. Such guanos usually contain 
from 12 to 15 per cent of nitrogen and from 12 to 15 per 
cent of phosphoric acid. The next poorer group generally 
ranges in nitrogen from 5 to 7 per cent and in phosphoric 
acid from 15 to 20 per cent. Finally, there is a group 
with from 3 to 5 per cent of nitrogen and from 20 to 25 
per cent of phosphoric acid. In regions of occasional 
rainfall the nitrogen, which in the excrement is chiefly 
in the form of uric acid, is changed by the action of mi- 
croorganisms very largely into ammonia and ammonium 
salts, which are readily leached away, together with the 
potassium salts. In consequence, there finally results 
a guano having a very low percentage of nitrogen and a 
high percentage of phosphate of lime, such, for example, 
as the Baker and Mejillones guanos. In humid regions 



78 FERTILIZERS 

the process even goes so far that the nitrogeneous ma- 
terials are not only entirely removed, but in some cases 
a considerable part of the phosphoric acid undergoes 
solution and subsequent transformation into phosphates 
of iron and aluminum, as, for example, on the island of 
Redonda. 

111. Color and physical character. — The color of 
guano is grayish-brown to yellowish-brown, the upper 
layers being lighter and the deeper ones darker, the in- 
tensity increasing usually with the depth. 

The physical character of guano varies more or less in 
different localities. 

112. Chincha Island guano. — The Chincha Island 
guano is said to be quite uniform and somewhat pulveru- 
lent, but it contains many irregular pieces and lumps 
ranging from three to, four inches in diameter down to 
particles no larger than rape seed. These lumps, which 
are whitish, grayish-white, reddish, or brownish, may 
have a dull, crumbling, fatty, or crystalline appearance. 
They are essentially concretionary in character, and from 
their analysis it appears that they consist of potassium 
sulfate; of ammonium, sodium, and potassium phos- 
phates; calcium sulfate, ammonium urate, ammonium 
oxalate, nitrogenous organic matter, and water. Some 
of the lighter and softer specimens of non-crystalline 
character have been found to contain as much as 14.8 
per cent of nitrogen. In some cases they consist chiefly 
of common salt and in others of ammonium phosphate. 
It sometimes happens, also, that small accumulations of 
whitish ammonium bicarbonate are found. These ma- 
terials indicate the brief periodic existence of conditions 
favorable to decomposition, such, for example, as might 
be caused by an occasional slight fall of rain. 



GUANOS 79 

113. Significance of oxalic acid and of oxalates in 
guano. — The presence in guano of oxalic acid, usually- 
combined as ammonium oxalate, is readily accounted for 
by the fact that it is a decomposition product of uric 
acid. For this reason when the uric acid content of guano 
is high, the percentage of oxalic acid is usually low, and 
vice versa. It was suggested by Liebig that the am- 
monium oxalate might be an important factor, in con- 
nection with ammonium sulfate, in effecting the solution of 
the tricalcium phosphate of the guano ; whereby calcium 
oxalate and ammonium phosphate would result. This 
conclusion is justified, according to Heiden, only by labo- 
ratory reactions. He does not consider it likely to take 
place in this manner in the soil itself, owing to the absorp- 
tive property of the soil for phosphoric acid and the tend- 
ency of the latter to unite with iron and aluminum oxids, 
which are normal constituents of most soils. 

114. Influence on the physical character of soils. — 
It cannot be expected that guano will have any long- 
continued and marked influence upon the physical char- 
acter of the soil, owing not only to the small amount 
employed per acre, but also to the nature of the organic 
matter which it contains. In this respect guano greatly 
resembles human excrement. 

115. The distribution and sources of guano. — The 
chief source of guano has been the mainland and especially 
a number of islands near the coast of Peru. These guanos 
have been called Peruvian guanos, or else they have 
received special names signifying the islands or the loca- 
tions on the coast from which they were obtained. Promi- 
nent among these islands are the Chinchas, Guanape, 
Balestas Lobos, Potillos, and Macabi. Some of the 
principal points on the mainland from which guanos have 



80 FERTILIZERS 

been procured are Chipana, Huanillos, Pabellon de Pica, 
Punta de Patillos, and Punta de Lobos. The many other 
islands and inland points from which guano has been 
secured are far too numerous to permit of their enumera- 
tion. 

From the shores and islands of Venezuela, Ecuador, 
and Colombia, guano was exported at an earlier date under 
the name of Colombian guano. Prominent among these 
guanos were the " Monks " and " Maracaibo " guano, 
from the coast of Venezuela, and the " Galapagos " 
guano from the island of that name off the coast of 
Ecuador. 

From Bolivia (now a part of Chili) came the Bolivian 
or Mejillones and several other guanos. 

Guano is found on the islands of Roza and Patos on 
the coast of Mexico and California, and in the Gulf of 
Mexico on the islands of Curacoa, Aruba, and Navassa ; 
also in the West Indies and in Labrador. On the west 
coast of Africa guano is found in a number of places, 
one of the best known of which is the island of Ichaboe 
(Itschabo) ; it occurs also in Australia, Asia, and between 
China and Japan, likewise at several points in Europe, 
on the Jarvis and Baker islands, as well as on a large 
number of islands belonging to other groups in the Pacific 
Ocean. 

The size -of some of these islands is very small. For 
example, Baker Island is only 1914 yards long by 1210 
yards wide, and it is less than 25 feet above sea level. 
Jarvis Island is but 1870 yards in its greatest dimension 
and but 1487 yards in the other, and it is but 30 feet above 
sea level. These islands are nevertheless visited by enor- 
mous numbers of birds, prominent among which are va- 
rious species of Pelacanus. 



GUANOS 81 

Recently, after supplying the needs of Cape Colony, 
there have been occasional exportations of Ichaboe guano. 
The material, however, is that which has been deposited 
within the limits of a year and contains many undecom- 
posed feathers. Its nitrogen content is about 8 per cent, 
but it contains less phosphoric acid than similar grades 
of Peruvian guano; it is also not so free as the latter 
from foreign matter. In recent years considerable guano 
ostensibly from the Chincha group of islands and from 
the island of Lobos has been imported into the United 
States, doubtless from the accumulations of recent years. 

116. Adulteration of guano. — In the early days of 
the trade in guano, many unprincipled middlemen found it 
highly profitable to adulterate it. The following are some 
of the materials which were employed for this purpose: 
viz. water, carbonate of lime, gypsum, magnesium sul- 
fate, sawdust, rice meal, common salt, sand, yellow loam, 
and other materials of such a character as to prevent 
their easy superficial recognition. In some cases low- 
grade guano was mixed with the good grades. Owing to 
the fact that there was at the outset no official inspection 
of such materials, the way of the transgressor was exceed- 
ingly easy. 

117. "Rectified" or "dissolved" guano. — When gua- 
nos are shipped to countries having a humid climate, 
there is more or less danger, especially in the case of those 
very rich in nitrogen, that they will absorb sufficient 
moisture to induce fermentation and the formation of 
ammonia. In the course of shipment, also, cargoes fre- 
quently become moistened by sea-water with the result 
that the urates become more or less broken down, a change 
accompanied by the formation of ammonium carbonate, 
which then undergoes ready dissociation, and consequent 



82 FERTILIZERS 

loss of ammonia. In recognition of this loss and the lesser 
value of such guano, its sale was for a long time forbidden 
under the regulations of the Peruvian government. In 
consequence, enormous quantities of it accumulated on 
the docks, especially at Hamburg and Rotterdam. 

Another reason for suppressing the sale of the damaged 
guano was that the importers, whose trade depended 
upon maintaining a high grade, hesitated to throw the 
damaged product into the hands of middlemen who 
would have been likely to sell it for, and in competition 
with, the uninjured material ; thus destroying the con- 
fidence of consumers and demoralizing the market. 

In 1864 Ahlendorff & Co. made a contract with the 
importers to handle this discarded material, and it was 
dried by a process which was said to accomplish the reten- 
tion of the ammonia. Soon after, this process was re- 
placed by treatment with sulfuric acid, and for the first 
time in the history of the sale of guano this firm offered 
it under a fixed guaranty of nitrogen and phosphoric acid. 
This treatment not only resulted in conserving the am- 
monia, but it also increased the availability of the phos- 
phoric acid. Both of these factors, and the definite 
assurance as to its composition, together with the frequent 
adulteration of the raw guano, soon resulted in its nearly 
driving the raw guano from the market, and the demand 
for the " rectified " product grew rapidly. 

118. The manner of using guano. — Owing to its 
ready decomposition and the consequent danger of losing 
ammonia, the raw guano is better adapted for use where 
it can be incorporated with the soil at the time of its 
application, than as a top-dressing for grass or other 
growing crops. The rectified guano is ideal, for the last- 
mentioned purpose, for the reason that its ammonia is 



GUANOS 83 

fixed by union with sulfuric acid, and much of the phos- 
phoric acid is also capable of being readily dissolved and 
carried into the soil. 

119. Guano a poorly balanced manure. — Such guano 
as is found in rainless regions is especially adapted to 
agricultural needs for the reason that it contains not only 
all three of the so-called essential elements, but, in addi- 
tion, lime, magnesia, iron, sulfuric acid, and other ingre- 
dients also occasionally of agricultural value. It is never- 
theless true that the proportion of potash is often too low 
to give the best results, for in the high-grade guano of 
the Chincha group of islands, which contains about 12 
to 16 per cent of nitrogen and 9 to 12 per cent of phos- 
phoric acid, the content of potash ranges only from about 
2.25 to 3.5 per cent. In the case of such guano, also, 
the ratio of phosphoric acid to nitrogen is too low to 
make the most economical and best-balanced manure for 
certain crops and soils. Again, the Lobos guano frequently 
contains as much as from 24 to 27 per cent of phosphoric 
acid and as little as from 2 to 3 per cent of nitrogen, with 
even less potash than is contained in the Chincha guano ; 
hence it is obvious that considerable additions of nitrogen 
and potash must be made in order to make it an ideal 
fertilizer for most crops and conditions. 

120. Bat guano unlike Peruvian and other guanos. — 
The so-called bat guano should not be confused with 
Peruvian guano, since, on account of the character of the 
food of the animal producing it (a mammal), it differs 
widely, even under the most favorable conditions, from 
the guano produced by birds living exclusively on fish. 

121. Appearance of bat guano. — The fresh excrement 
of the European bat resembles in form that of the mouse, 
but it is not so compact, and it presents a glistening appear- 



84 FERTILIZERS 

ance on account of the presence in it of undigested insect 
wings and other residues. Bat guanos are usually pul- 
verulent and are ordinarily quite dry and odorous ; some- 
times, however, they occur as heavy, doughy, inodorous 
masses. 

122. Where bat guano is found. — The bat is a vora- 
cious eater and hence accumulates large quantities of 
dung in caves, grottos, church steeples, and similar dark 
and obscure places to which it can gain access. 

123. Chemical composition of bat guano. — The fresh 
dung is said by Hardy to contain about 60 per cent of 
water, but in bat guano the amount of water usually 
ranges from 12 to 25 per cent. The content of nitrogen 
may range from 1 to 12 per cent, the greater portion of it 
being present in ammonium salts associated with small, 
or occasional large, quantities of nitrates and more or less 
nitrogen in organic matter. The quantity of phos- 
phoric acid is also widely variable, the minimum being 
about 2.5 per cent, and the maximum about 16 per cent. 
The presence of large amounts of nitrates, in some cases, is 
attributed to the material having rested on limestone 
rock at points where there is ready access of air and at 
least a fair amount of moisture. Like all such materials, 
they often contain considerable earthy matter. 

124. Distribution of bat guano. — Deposits of bat 
guano are widely distributed in North America, the 
West Indies, Spain, Sardinia, France, the islands of the 
Indian Ocean, and elsewhere. Some of the most extensive 
deposits in the United States have been found in Texas 
and Arkansas ; a single deposit in some of these cases 
amounting to as much as 20,000 tons. 

125. Precautions in the use and purchase of bat guano. 
— From what has preceded it will be seen that bat guano 



GUANOS 



85 



varies as widely in composition as the ordinary guanos 
from the rainless and more or less rainy regions. The 
best specimens approach in nitrogen content the Chin- 
cha and other high-grade guanos, whereas the poorest 
contain even less nitrogen than the Lobos guano. The 
usual amount of phosphoric acid present is from 3 to 7 
per cent, although it sometimes reaches an upper limit of 
16 per cent, as, for example, in a quite fresh deposit in 
Arkansas. The content of potash is usually very low, 
rarely exceeding 2 per cent, and it is frequently less than 
1 per cent. The following are averages given by Goess- 
mann : — 



Nitrogen . . 
Potash . . . 
Phosphoric acid 



Average of Nine 

Samples of Bat 

Guano from Texas 



6.47 
1.31 
3.76 



Average of Two 

Samples of Bat 

Guano from Florida 



9.74 
1.77 
3.35 



It is evident from the foregoing that such guano should 
be bought and sold solely on the basis of its chemical 
analysis. 

126. Bat guano needs supplementing. — In most cases 
these guanos must be supplemented by applications of 
potassium salts and by readily available phosphatic 
fertilizers, if they are to be used in the most economical 
way. 



CHAPTER VIII 

FISH, CRAB, LOBSTER, AND SIMILAR WASTES 

The term " fish guano " is often applied to fish and 
fish wastes, but since it is in no strict sense guano, as im- 
plied by the Spanish origin of the name, it is more properly 
considered under a separate chapter. 

127. Fish long used as a fertilizer. — The use of fish 
and of fish waste as a fertilizer by people living near the 
ocean, or wherever fisheries flourish, has long been prac- 
ticed. In fact, the American Indian was no exception, for 
he had already learned to apply fish as a fertilizer for his 
maize when the Europeans first landed on the shores of 
North America. 

128. Early catching of fish for fertilizer purposes. — 
As early as 1872 the catching of fish, which were employed 
for fertilizing the soil for both wheat and hops, had become 
quite an industry on the coasts of Essex, Kent, and Sussex, 
in England. The fish, which were very small, were a 
variety of herring (Clupea sprattus). They were sub- 
jected to a stamping and crushing process and were ap- 
plied to the soil without further preparation. 

129. Special processes for preparing fish for fertilizer 
uses. — In 1853 Petlitt patented a process for the prep- 
aration of a fertilizer from herring. The nitrogen con- 
tent of this prepared material ranged from about 11.2 to 
13.8 per cent. 

Shortly after the middle of the preceding century 
Ch. de Molon, who had already convinced himself by 

86 



FISH, CRAB, LOBSTER, AND SIMILAR WASTES 87 

practical trials on his estate on the coast of Brittany of 
the manurial value of the wastes from the sardine fisheries, 
conceived the idea of treating the material in such a way 
as to prevent its rapid decomposition and render it trans- 
portable to long distances. To this end De Molon as- 
sociated with himself Thurneyssen, and they erected a 
factory near Brest, in which to carry out the process. 
This, in brief, consisted in heating the fish with steam 
applied between the walls of a double-walled kettle at a 
pressure of three and one-half atmospheres (140° C), 
after which it was pressed. In this process the amount 
of oil recovered from the top of the waste liquors repre- 
sented about 2 to 2.5 per cent of the fresh fish. The 
waste liquors, because of their high nitrogen content, some- 
times created a nuisance, on which account they were 
often evaporated, whereby the solid matter was saved. 
The remaining cake was passed through a machine which 
rubbed it into a thick dough, in which state it was taken 
to the drying room and subjected to a temperature of 
from 48° to 56° R., until it was ready for grinding, in 
final preparation for shipment. The dry product ready 
for marketing represented about 22 per cent of the original 
weight of fish. 

130. Fish wastes in Japan. — In Japan herring are 
likewise utilized for the manufacture of oil and fish-scrap, 
the latter being used without further manipulation, in 
fertilizing tea plants, tobacco, cotton, and other crops. 

131. Fish wastes in Newfoundland. — In connection 
with the Newfoundland cod fisheries, the heads, entrails, 
bones, and other waste portions of the fish, to the amount 
of 700,000 tons annually, were cast into the sea until De 
Molon sent his younger brother to the Island to erect a 
factory for the preparation of fish guano for export. 



88 FERTILIZERS 

132. Norwegian wastes from cod and whales. — In 
Norway fish guano is prepared from the wastes of the cod- 
fishing industry and from whales. The number of cod- 
fish said to be taken annually in that country amounts to 
from 18,000,000 to 20,000,000. A considerable number 
of factories are engaged in the preparation of the waste 
for fertilizing purposes. The finished product has a white 
to brown color and usually contains from 8.5 to 11 per 
cent of water, 8 to 10 per cent of nitrogen, and 12 to 14 
per cent of phosphoric acid. 

133. Methods of handling Menhaden in the United 
States. — The method of handling the Menhaden (a sort 
of herring also called pogys, Aha menhaden) now prac- 
ticed in the United States, varies somewhat in the differ- 
ent works. In some places the former method of unloading 
from vessels by means of tubs holding 3| barrels, or about 
1000 fish, is still in vogue. By that method from 80,000 
to 100,000 fish can be discharged per hour. The tubs are 
raised by means of a steam hoister installed on the steamer 
and used in raising to the deck the fish caught in the seines. 
In certain instances, also, they are raised by hoisters located 
at the dock. From the tubs the fish are passed to a re- 
ceiving box, from which they are taken into cars. They 
are then hauled up an inclined track by another hoister 
and delivered into wooden vats, well provided with steam 
pipes. Each of these vats holds about 20,000 fish. Here 
they are cooked until they are ready for pressing in power- 
ful hydraulic presses which leave a product containing 
from 50 to 60 per cent of moisture. The scrap is then 
either treated with sulfuric acid, in order to prevent its 
decomposition, or it is sun-dried on platforms. At present 
most of the factories are equipped with elevators which 
transfer the fish to the receiving boxes and conveyors at 



FISH, CRAB, LOBSTER, AND SIMILAR WASTES 89 

the rate of 250,000 or more per hour, for each elevator in 
operation. From the elevator the fish are carried into 
iron cookers of various sizes, which are from 20 to 30 feet 
long, and from 2 to 3 feet in diameter. The fish pass 
through these cylinders, subjected to a continual steam 
pressure of 100 pounds to the square inch, at the rate of 
from 100,000 to 150,000 per hour ; they then pass, by a 
conveyor, directly into screw presses of various sizes. 
The larger presses now in use have a capacity of 150,000 
fish per hour. Upon leaving the presses the scrap is 
carried, largely by means of conveyors of various types, 
to the acidulated scrap storage or to the dryers, as desired. 
In some cases the scrap is treated with sulfuric acid and is 
then transferred directly to vessels lying alongside of 
those which are discharging the fish. 

134. Fish waste treated with sulfuric acid. — Attempts 
have been made to treat the fish waste with considerable 
quantities of sulfuric acid, but this has proved to be a very 
difficult operation ; and in but few instances is the char- 
acter of the fish products such that this treatment is 
considered practical. The amount of water in such treated 
material may range from 13 to 18 per cent, the total nitro- 
gen from 7 to 9 per cent, and the total phosphoric acid 
often from 1 1 to 12 per cent. By this treatment two-thirds 
of the phosphoric acid is rendered immediately soluble in 
water. A part of the nitrogen may be changed into 
ammonia, and, under the usual conditions, about one-third 
of it is thus changed. 

135. Chemical composition and utilization of whale 
products. — Fresh whale-meat contains about 44 per cent 
of water, 23 per cent of fat, 32 per cent of flesh, and 1 per 
cent of ash. In its undried condition it contains about 
4.8 per cent of nitrogen, but when fully dried the nitrogen 



90 FERTILIZERS 

content is about 8.7 per cent. The whale-bone, with a 
content of 3.84 per cent of water, contains 1.3 per cent of 
fat, 34.6 per cent of organic matter, and 60.2 per cent of 
ash. The nitrogen amounts to 3.5 per cent. In the man- 
ufacture of fertilizer from the bones and meat of whales, 
the fat content is so great that many difficulties are met 
in making the separation. The whale glue which is 
unfit for other purposes finds its way into fertilizers. It 
contains approximately 8.4 per cent of nitrogen and 3.2 
per cent of phosphoric acid. Whale flesh, when dried and 
freed from fat, contains from 14 to 15 per cent of nitrogen. 
A so-called " whale guano," with from 7 to 8 per cent of 
nitrogen and 9 to 10 per cent of phosphoric acid, and whale- 
bone meal with 4 per cent of nitrogen and 21 per cent of 
phosphoric acid, have been offered in the market. 

136. Availability and use of fish guano. — The avail- 
ability of the nitrogen of fish guano stands close to that of 
dried blood. Like all such organic nitrogenous materials, 
the nitrogen is not so quick in its action as that in nitrate 
of soda, potassium nitrate, or even in sulfate of ammonia. 
There are several important conditions upon which its 
transformation into nitrates and its consequent efficiency 
very largely depends; as, for example, the temperature, 
moisture, soil reaction, the fungi, and the bacterial flora 
of the soil. Because of the several conditions necessary 
to the transformation of the nitrogen of such materials 
into ammonia and eventually into nitric acid, it is 
usually best to incorporate it with the soil rather than 
to use it as a top-dressing. Though not absolutely nec- 
essary, it is desirable that fertilizer ingredients of this 
• character, if applied in large quantities, should be incorpo- 
rated with the soil several days before the seed is planted. 
In this way possible injury to the plant seedlings, which 



FISH, CRAB, LOBSTER, AND SIMILAR WASTES 01 

might arise in connection with the processes of fermenta- 
tion, may be avoided. 

137. Fish guano requires supplementing. — Owing to 
the high percentage of nitrogen present in fish guano, it 
should usually be applied in conjunction with bone, or 
preferably with basic slag meal or with acid phosphate, or 
other superphosphates. It is usually important, also, that 
it be properly supplemented with suitable potassium salts. 

138. Fish scrap may be employed without further 
treatment. — As a rule the fish scrap is sold directly to 
fertilizer manufacturers, but whenever it and the waste 
untreated fish or parts of fish are obtainable at low cost, 
near where they can be utilized, they can be employed 
advantageously bj r spreading them on the surface of 
the land and plowing them under as one would use 
stable manure. 

139. The value of fish waste depends on the climate 
and soil. — It is reported by Kellner that in certain parts 
of Japan fish scrap, owing to the warm climate, moisture, 
and other conditions favorable to decomposition, is a 
quick-acting fertilizer ; but in very cold countries, where 
the reverse conditions prevail, its action is slow and is 
especially unsatisfactory early in the spring. For many 
reasons such material is much better adapted for use on 
sandy or naturally open soils than on compact silts and 
clays. 

140. Shrimps. — Along the coast of the North Sea 
there are found millions of shrimps (Crangon vulgaris), 
which, though prized as a great delicacy for human food, 
are used at times in great quantities in the manufacture 
of fertilizer. Since the product is relatively poor in phos- 
phoric acid, it is often supplemented by additions of bone 
or of other phosphatic fertilizers. 



92 FERTILIZERS 

141. The king-crab. — In the United States the king- 
crab (also known as horse-foot or horse-shoe ; Limulus 
Americanus) has not only been utilized directly as a fer- 
tilizer, but it has also been dried, ground, and sold under 
the name of " horse-foot guano." It has often been used 
as an ingredient of various commercial fertilizers. In 
a dry state this material contains, as found by Voorhees, 
about 10 per cent of nitrogen, which apparently possesses 
a high degree of availability. According to Storer, it is 
necessarily poor in phosphoric acid, as is shown by the 
fact that the dried shells, after being freed of the flesh 
attached to the upper portions and to the legs, contained 
but 0.26 per cent of phosphoric acid. They contain only 
0.06 per cent of potash, but the content of nitrogen has 
been found to be equal to as much as 12.55 per cent. 

142. The common crab. — According to Storer, the 
common crab (Lupa dicantha Milne-Edwards) collected 
on the shore of Massachusetts was found to contain 3.6 
per cent of phosphoric acid, 0.2 per cent of potash, and 
1.95 per cent of nitrogen. 

143. Lobster refuse. — The shells of cooked lobsters 
(Homarus Americanus Milne-Edwards), are reported by 
Voorhees as containing, when dry, an average of 3 per 
cent of phosphoric acid, 20 per cent of lime, and 4 per 
cent of nitrogen. An analysis of lobster shells reported 
by Goessmann, shows that they contained 7.3 per cent of 
water, 4.5 per cent of nitrogen, 3.5 per cent of phosphoric 
acid, 22.2 per cent of lime, and 1.3 per cent of magnesia. 

144. Star-fish. — In the case of fresh star-fish examined 
at the Rhode Island experiment station it was found, after 
rinsing with fresh water and removing the superficial 
moisture, that they lost, upon drying, 64.4 per cent of 
their weight. The mineral matter remaining after they 



FISH, CRAB, LOBSTER, AND SIMILAR WASTES 



93 



were incinerated, amounted to 20.3 per cent. The fresh 
undried star-fish contained 9.62 per cent of lime, 0.23 per 
cent of potash, 0.20 per cent of phosphoric acid, and 1.8 
per cent of nitrogen. The value of these ingredients in a 
ton of fresh star-fish, based upon the recent ruling prices 
for lime and the other ingredients, would range from about 
$6 to $7.50 per ton. 

It is reported that on the French and Belgian coasts of 
the North Sea a mixture of certain mollusks with star-fish 
is employed as a manure, under the name " Coquilles 
animalisees." 



CHAPTER IX 

COMMON SLAUGHTER-HOUSE NITROGENOUS WASTE 
PRODUCTS 

The number of waste nitrogenous animal substances is 
so large, and they are so important, that they demand 
individual mention. 

145. Dried meat meal. — Among the trade names which 
have been applied to various preparations of dried meat 
meal are " animal matter," " dried meat," " azotin," and 
" ammonite." These materials are produced in the process 
of rendering dead animals, meat refuse, and as a waste 
product from the manufacture of meat extract. In the 
preparation of such extracts much of the phosphoric 
acid is removed, on which account certain Australian prod- 
ucts have been placed on the market mixed with bone 
meal. These contain about 6 per cent of nitrogen and 
about 13 per cent of phosphoric acid. 

The rendering process. — In the rendering process refuse 
bones and meat are placed in steel tanks where they are 
subjected for a few hours to a steam pressure of from 40 
to 60 pounds, or higher. As a result of this treatment the 
fat is separated and the bones are rendered highly friable, 
in consequence of which they can be easily ground. After 
the removal of the hot liquors the fat rises to the surface 
of the liquid, where it solidifies upon cooling ; the meat is 
also separated from the bones, after which it is dried and 
ground. 

94 



SLAUGHTER-HOUSE WASTE PRODUCTS 95 

146. All readily utilized by fertilizer manufacturers. — 
Before the manufacture of fertilizers had grown to its 
present proportions, these meat residues were readily avail- 
able to the farmer, but now that the supply fails to keep 
pace with the demands, the manufacturers of " complete " 
fertilizers readily absorb the entire supply. 

147. Chemical composition of meat meal. — The 
amount of nitrogen in the best of the meat meals ranges 
usually from 13 to 14 per cent ; though they may contain 
as little as 10 per cent, according to the amount of im- 
purities and moisture present. In addition to nitrogen 
the meat meals contain varying percentages of phosphoric 
acid, depending in amount upon their origin and the quan- 
tity of bone associated with the meat. 

148. Availability of meat meal. — In the availability 
of their nitrogen, these waste meat materials stand, accord- 
ing to Wagner, somewhat behind dried blood, horn meal, 
and tender plants, and on about the same plane as nitrogen 
in fish guano, bone, and bone tankage ; hence they stand 
in the next to the best group of organic nitrogenous ma- 
nures. 

149. The nature of bone tankage. — Bone tankage 
consists of rendered or steamed bone associated with a 
considerable quantity of meat, cartilaginous matter, and 
other substances. It is prepared from the animal refuse 
secured from slaughter-houses and meat markets. 

150. Composition of bone tankage. — Its nitrogen 
content may range from 4 to 12 per cent and its content 
of phosphoric acid from 7 per cent to approximately 20 
per cent. In the United States six commercial grades are 
often recognized with 18, 16, 13.5, 11.5, 9, and 7 per cent 
as the respective minimum percentages of phosphoric acid. 
It is obvious that these are mere arbitrary subdivisions, 



96 FERTILIZERS 

and that any one grade must range up to the next higher 
just as the highest of the bone tankages range up to the 
minimum of what is recognized in the trade as bone. 

151. Value of bone tankage as a fertilizer. — The value 
of bone tankage as a fertilizer depends to a considerable 
extent upon its degree of fineness. The importance of 
this feature is greater, the larger the quantity of bone, 
and consequently the higher the percentage of phosphoric 
acid. It is probable that the fertilizing value of the nitro- 
gen in bone tankage does not differ materially from that 
in bone, fish, and meat meal, and it should logically stand 
between the first two. 

152. Method of employment. — The best method for 
the employment of bone tankage is to introduce it into the 
soil in finely ground form, rather than to use it in a coarse 
condition or to employ it as a top-dressing. 

153. Chemical composition of red dried blood. — The 
red dried blood, which differs from the black blood in its 
method of preparation, possesses ordinarily the higher 
commercial value, and usually contains from 13 to 14 per 
cent of nitrogen, though if imperfectly dried it may con- 
tain much smaller percentages. 

154. Chemical composition of black dried blood. — 
Black dried blood as commonly offered in the market may 
range in nitrogen content from 5.5 to 12 per cent, and es- 
pecially good lots have been found to contain over 13 per 
cent. 

155. Reasons for occasional low nitrogen content of 
blood. — The low content of nitrogen sometimes found in 
dried blood may be due to. the incidental or intentional 
introduction, in the course of its handling and manufac- 
ture, of more or less bone and tankage. It may also be 
due to its adulteration with pulverized roasted leather, 



SLAUGHTER-HOUSE WASTE PRODUCTS 97 

pulverized peat, or other substances, the detection of 
which, by casual inspection, and even in some cases by 
chemical or other means, has heretofore been difficult or 
impossible. If the blood contains much tankage or bone, 
there will be much more phosphoric acid present than the 
small quantity normally associated with pure blood. 

156. Chemical composition of the better commercial 
blood. — The better grades of commercial dried blood 
usually contain from 13 to 14 per cent of water, from 10 
to 13 per cent of nitrogen, 0.5 to 1.5 per cent of phos- 
phoric acid, and from 0.6 to 0.8 per cent of potash, 
though it is ordinarily sold without reference to any- 
thing but its nitrogen content. 

157. Crystallized blood. — What is known as "crys- 
tallized " dried blood is produced by evaporation at a 
temperature of about 60° C, and it is capable of being 
redissolved. Owing to its cost, it is usually employed for 
industrial rather than fertilizing purposes. 

158. Certain processes of preparing dried blood. — In 
the process of transforming blood into the dried market- 
able material, it is agitated vigorously and is at the same 
time treated with steam in a vessel with a perforated false 
bottom. As a result of the raised temperature, coagula- 
tion of the fibrin and albumen takes place, after which the 
slightly reddish liquid portion is withdrawn. After dry- 
ing, the blood is milled to a proper degree of fineness. 
The yield of dried blood is above 20 pounds per 100 pounds 
of the original material. The coagulation is often has- 
tened by the addition of a small amount of concentrated 
sulfuric acid. Sometimes from 2 to 3 per cent of pul- 
verized quicklime is added to the blood before flocculating. 
In consequence of this addition, any ammonia in the waste 
water is disengaged, and the material can then be dried in 



98 FERTILIZERS 

the air, if desired, with the result that a practically odor- 
less fine powder is produced. 

If blood is allowed to stand for some time, after adding 
from 1.3 to 3 per cent of lime, the mass will solidify and 
can be subsequently air-dried with ease and without under- 
going decomposition. 

In the process of drying and preparing dried blood, a 
mixture of iron sulfate, sulfuric acid, and sodium nitrate 
is often added. The coagulation in such cases is very 
rapid, and the material gives off no bad odors during the 
process of drying. It is not practical for this purpose to 
use solely the commercial iron sulfate, for if this is done 
there results a pasty mass which does not dry readily. 
In order to obviate this difficulty, a mixture of sulfate of 
iron and of alum is sometimes employed ; also treatment 
of the blood with calcium carbonate (chalk) and peat ; 
and precipitation with alkaline sulfates or phosphates 
and acid ferric sulfate. 

159. Dried blood, if very fine, is highly hygroscopic. — 
The finer the blood is ground, the more hygroscopic it 
becomes, and when made excessively fine the water con- 
tent has been known to reach 27 per cent. This high 
moisture content is, however, not desirable in material 
which must be stored, for too much moisture is likely to 
lead to changes resulting finally in a loss of ammonia. 

160. Availability of blood dependent upon soil condi- 
tions. — Dried blood is the best, or one of the best, organic 
nitrogenous fertilizers, but like others it is dependent for 
its efficiency upon the character of the soil. This is well 
shown by experiments made with it on upland silt loam 
soil, at the Rhode Island experiment station, in which the 
availability of the nitrogen in an excellent lot of black 
dried blood, containing slightly over 13 per cent of nitro- 



SLAUGHTER-HOUSE WASTE PRODUCTS 99 

gen, was considerably less than one-half as great as in 
nitrate of soda, whereas after liming the soil, the avail- 
ability of the nitrogen rose to over 90 per cent of that in 
nitrate of soda. 

161. Processes of preparing horn meal and hoof meal. 
— In the various manufacturing establishments where 
horn is employed, there is a large lot of waste material. 
The preparation of such horn waste, and of hoofs, for fer- 
tilizing purposes, is sometimes accomplished by subjecting 
them for about twelve hours to steam pressure, after which 
the material is dried and ground to a fine powder. It is 
then sold as horn meal and hoof meal. Another method 
of manufacture is to subject the materials to high tempera- 
tures, even frequently to the extent of slight roasting, 
after which they can be easily pulverized. In consequence 
of the loss of water in this process the nitrogen content is 
raised materially. 

162. The chemical composition of horn meal. — A 
very pure sample of horn meal is reported as containing 
9.5 per cent of water, 87.4 per cent of organic matter, and 
1.69 per cent of ash, in addition to small amounts of 
impurities. 

The amount of nitrogen present in horn (in keratin) is 
about 14.1 per cent, phosphoric acid 0.28 per cent, and lime 
0.48 per cent. 

Certain English writers report the range of nitrogen in 
commercial samples of horn meal to be from 7 to 15 per 
cent. 

163. Chemical composition of horn and hoof meal. — 
A sample of mixed horn and hoof meal, from a lot in which 
hoofs were used which had a small amount of bone adher- 
ing to them, was found by C. Peterson to contain 13 per 
cent of nitrogen and 5.5 per cent of phosphoric acid. 



100 FERTILIZERS 

Samples are reported from France as containing from 16 
to 17 per cent of nitrogen. The analyses of three different 
lots of hoof and horn meal are reported by Goessmann in 
which the minimum of nitrogen was 1 1 per cent and the 
maximum 15.5 per cent. 

164. The nitrogen content of hoof meal. — The average 
nitrogen content of hoof meal is generally held to be about 
12 per cent. 

165. The efficiency of hoof meal. — Hoof meal in its 
natural condition is held by Voorhees, Murray, and others 
as being of little value, even though finely ground ; and 
some authorities assert that even after steaming, the value 
of the nitrogen is still far below that in blood and tankage. 
It is nevertheless superior to leather, wool waste, and hair, 
and Heiden ranks it as a very effective nitrogenous fer- 
tilizer (Dtingerlehre, 2, 746). 

166. The adulteration of horn and hoof meals. — It is 
reported that horn meal and hoof meal are sometimes 
adulterated with ground nut shells and other difficultly 
recognizable sustances. On this account, in purchasing 
such materials, one should buy only on the basis of a 
guaranteed analysis. The adulteration may explain 
much of the discordant testimony as to the agricultural 
value of these materials, for it does not appear that the 
genuineness of the lots employed in certain experiments 
was always determined. 

167. Preparatory treatment of waste leather. — Large 
quantities of leather waste are now said to be employed 
in the manufacture of ready-mixed fertilizers. In its 
preparation for such use a wet acid or " chamber " pro- 
cess, involving a simultaneous treatment of raw phosphates, 
is applicable, as it is under certain conditions to many of 
the other waste nitrogenous materials. Waste leather is 



SLAUGHTER-HOUSE WASTE PRODUCTS 101 

also treated with steam, in the same way as hoof meal and 
horn meal. It is then dried and ground, or in lieu of 
steaming it is often roasted and ground. The value of 
such prepared leather, unless it is subjected to the " cham- 
ber " process, is very small in any case, although it is 
slightly greater if steamed than if roasted. Owing to the 
destruction of the tannin in the roasting process, the 
leather thus prepared is said to be selected as an adulter- 
ant of dried blood and of certain other high-grade nitro- 
genous substances, on account of the difficulty of its 
recognition. 

168. The chemical composition of prepared leather 
waste. — The leather meal prepared by the steaming or 
roasting processes contains from 7 to 9 per cent of nitro- 
gen and from 0.5 to 1 per cent of phosphoric acid; al- 
though it may sometimes range slightly above or below 
these figures. 

169. The availability of nitrogen in leather. — If em- 
ployed on a soil in which the conditions for nitrification 
are poor, the value of the nitrogen of roasted leather may 
be even less than one-hundredth as great as that of the 
same quantity in nitrate of soda ; if, however, the condi- 
tions for nitrification are ideal, its value may rise to from 
13 to 20 on the basis of 100 for the nitrogen in nitrate of 
soda. At all events, such leather is one of the least valu- 
able of the nitrogenous fertilizers. It is obvious, therefore, 
that roasted or steamed leather meal, if employed directly 
as a fertilizer, is not worth the cost of transporting to very 
great distances. It is, however, probable that by the sul- 
furic acid or " chamber " process a considerable part of 
the nitrogen is changed into sulfate of ammonia and that 
the organic residues remaining are also rendered still more 
available to plants. 



102 FERTILIZERS 

170. Treatment of leather with carbonates of the al- 
kalies. — It has been proposed by Reichardt to treat 
waste leather with carbonates of the alkalies. Before 
being subjected to such treatment, powdered leather was 
found to be soluble in hot water to the extent of but 15.8 
per cent, but after being left in contact with a 5 per cent 
solution of sodium carbonate for several days, it was 
soluble to the extent of 28.8 per cent. This method of 
treatment has, however, apparently never found any exten- 
sive application in practice. 

171. Leather really not so valuable as it appears. — 
The inefficiency of the nitrogen in leather meal, as com- 
pared with that in the better class of nitrogenous materials, 
is not shown adequately by merely the smaller weights of 
the resultant crops, since crops grown with the aid of an 
abundance of readily available nitrogen are often richer 
in that element, and hence possess a greater feeding value 
than those grown with poorer and less available materials, 
like leather. This is well illustrated by experiments by 
S. W. Johnson in which nitrogen in blood, at the rate of 
20 pounds per acre, gave four times as great an increase 
in crop as the same amount of nitrogen in horn. The in- 
crease of nitrogen in the crop was also nearly twice as great 
in the former as in the latter case. With 40 and 60 pounds 
of nitrogen per acre, the same principle held true, although 
the proportionate increases were not the same as in the 
first instance. 



CHAPTER X 

OTHER MISCELLANEOUS NITROGENOUS SUBSTANCES 

A considerable number of plant residues and of other 
miscellaneous materials of somewhat uncommon occur- 
rence are often used for manurial purposes. These will 
now be considered. 

172. Feathers. — Clean feathers, according to the analy- 
ses of Payen and Boussingault, contain 15.3 per cent of 
nitrogen. The sweepings from a feather warehouse, how- 
ever, contained but 6.25 per cent of nitrogen, indicating 
the presence of much foreign matter. 

Feathers decompose slowly in the soil, and hence they 
have a small positive value as a fertilizer, even without 
special treatment. 

173. Hair bristles and wool. — The hair of various 
animals, the bristles of swine, and wool all contain es- 
sentially the same amounts of nitrogen as feathers. In 
other words, if free from all impurities, they contain from 
14 to 15 per cent of nitrogen. After drying at 250° F., 
human hair has been found to contain 17 per cent of 
nitrogen. 

174. Tannery hair. — Hair from tanneries contains more 
or less foreign matter and water, which lessen the nitro- 
gen content. The amount of nitrogen found in such hair 
ranges from 5.5 to 8 per cent, the average being about 6.5 
per cent. Certain of the calcareous wastes of the tanner- 
ies, charged with organic matter derived from the cleans- 

103 



104 FEETIL1ZEE8 

ing and preparation of hides, contain from 2.8 to 3.4 per 
cent of nitrogen. 

175. Waste silk. — The nitrogen content of waste silk 
and silk rags ranges from 8 to 11 per cent of nitrogen, 
depending upon the purity of the materials. 

176. Wastes from hares and rabbits. — In the prep- 
aration of the hair of hares and rabbits for the manufac- 
ture of hats, the ears, tails, legs, and irregular parts of 
the skin often accumulate in considerable quantities as 
waste matter. This material, according to C. Thiel, has 
been found to contain 7 per cent of nitrogen, 0.6 per cent 
of potash, and 1.7 to 3.1 per cent of phosphoric acid. 

177. Chemical composition of waste wool. — Wool 
waste may contain from 0.5 to 7 per cent of nitrogen, 
dependent upon the amount of water and of foreign matter 
which is present. The range in the water content is 
usually from 15 to 50 per cent. Various methods have 
been proposed for utilizing this and other nitrogenous 
materials. 

178. Wool waste as a manure. — Wool waste has long 
been used in its natural condition as a manure for hoed 
crops and in preparation for seeding to grass ; and, like 
coarse stable manure, it is best to spread it broadcast 
and turn it under with a plow. Its use is seldom to be 
recommended, excepting where the transportation charges 
and the cost of application are small. 

179. Effect of superheated steam on wool waste. — 
When wool waste is subjected to high steam pressure, 
it assumes a liquid condition. Upon subsequent evapora- 
tion there remains a dark brown powder said to be very 
largely soluble in water and supposed to consist of leucin 
(C 6 Hi3N0 2 ), tyrosin (C 9 HnN0 3 ), and other related amid 
compounds. 



MISCELLANEOUS NITROGENOUS SUBSTANCES 105 

180. Concerning Petermann's tests of availability. — 
Experiments by Petermann, conducted in the field and in 
pots, have appeared to show that notwithstanding that 
the nitrogen of wool is rendered more available by the 
process of steaming, it is still much inferior to nitrogen 
in nitrate of soda. These experiments were made with 
spring wheat and with beets in conjunction, in certain 
cases, with phosphates, but without potassium salts. It 
is interesting, in view of the omission of potash, to note 
that the nitrogen in nitrate of soda appeared to possess 
relatively greater superiority for the beets than for the 
wheat. This, in the light of observations made by Hell- 
riegel, Wilfarth and others in Germany, and by Wheeler 
and Hartwell at the Rhode Island experiment station, 
indicates a probable direct or indirect manurial effect of 
the soda, the first or both of which would be expected to 
be greater in connection with beets than with wheat. 
Owing to this failure to provide an abundance of potash 
and to recognize the possible beneficial alkaline effects 
arising from the residual sodium carbonate formed from 
the nitrate, too great value was doubtless attached to the 
nitrogen in nitrate of soda, and too little to the effect of 
steaming as a means of increasing the efficiency of the 
nitrogen of the wool waste. 

181. Soluble wool waste not subject to loss by leaching. 
— It was found by Petermann that practically none of 
the soluble nitrogenous organic matter was lost from the 
soil by leaching, in which respect it possesses certain dis- 
tinct advantages in open soils. 

182. Benefit from steaming not equally applicable 
to all other nitrogenous wastes. — Attention has been 
called by S. W. Johnson to the fact that the availability 
of certain materials, such as bones, tendons, and hide, 



10G FERTILIZERS 

which yield glue, may be injured by steaming, incase the 
glue is not removed. This is said to be due to the cement- 
ing action of the glue, on account of which the decomposi- 
tion of the material in the soil is hindered ; nevertheless, 
horn, hoof, hair, wool, and certain other materials are 
benefited by the treatment. 

183. The production of garbage tankage. — Garbage 
tankage is the product derived from the treatment of 
kitchen wastes, and it may be composed of materials of 
both vegetable and animal origin. The refuse is treated 
with steam at high pressure, as a result of which it is 
completely disinfected, and much of the water is expelled. 
This product is then extracted by benzene, which is sub- 
sequently recovered and used for the repeated extraction of 
new lots of material. The extracted residue is then screened, 
in order to permit of the recovery of the bones and of other 
miscellaneous materials, in separate portions. It is said 
by Storer that 30,000 pounds of kitchen waste have been 
found to yield by this process 1800 pounds of grease and 
12,000 pounds of garbage tankage. In this process the 
vapors are condensed and passed into the sewers, and the 
various operations are said to be practically unaccom- 
panied by odors. 

184. The fertilizer value of garbage tankage low. — 
Such garbage tankage is of rather low value as a manure. 
It is used by a few fertilizer manufacturers, some of 
whom fortunately submit it to the so-called " wet cham- 
ber " process, by which its value as a fertilizer is at least 
somewhat improved. 

It usually contains from 2.5 to 3 per cent of nitrogen, 
1.5 to 3 per cent of phosphoric acid, and from 0.7 to 1.5 per 
cent of potash. 

185. The character of shoddy and felt refuse. — The 



MISCELLANEOUS NITROGENOUS SUBSTANCES 107 

term "shoddy," as formerly used, referred to short frag- 
ments of wool rejected in various woolen industries. Now, 
however, the name is often applied to wastes of both silk 
and wool. 

186. Chemical composition of shoddy and felt. — 
Shoddy usually contains from 4 to 12 per cent of nitrogen, 
the average content being about 6.5 per cent. 

A felt refuse examined by Goessmann was found to 
contain "5.26 per cent of nitrogen. It may therefore be 
classed as of about the same general character as 
shoddy. 

187. The use of felt and shoddy wastes as manures. — 
Felt and shoddy wastes are highly esteemed as a manure 
for grapes and certain other fruits, and especially for 
hops. This is supposedly due to the fact that these crops 
do not require a large amount of nitrogen at any given 
time, but thrive best where the supply, though small, 
is continuous throughout the season. For such pur- 
poses shoddy is considered as one of the best substi- 
tutes for farm-yard manure, and in many cases it is 
even chosen in preference to the manure. From 1 to 
2.5 tons of shoddy are considered equal to 20 tons of 
farm-yard manure. 

Shoddy not only exerts a direct manurial action, due 
to its high content of nitrogen, but it also improves very 
greatly the physical condition of certain soils. 

188. The character of soot. — Soot consists chiefly of 
finely divided particles of carbon which are deposited in 
chimneys during the imperfect processes of combustion. 
On account of its finely divided physical condition, it 
condenses gases upon its particles to a high degree, and 
hence often becomes rich in ammonia which it has ab- 
sorbed from the gaseous products of combustion. 



108 FERTILIZERS 

189. The chemical composition of soot. — The nitrogen 
content of soot may range from about 0.5 to 6 per cent, 
the average being about 3.2 per cent. 

190. Soot benefits physically. — Owing to its dark 
color, soot is supposed to cause soils upon which it is spread 
to absorb more heat, thus forcing the crop and creating 
conditions favorable to bacterial activity. When it is 
introduced into soils it also improves their physical con- 
dition, especially if they are of a clayey texture. 

191. Soot rarely toxic. — A sample of soot has been 
reported in Europe which was found to be toxic to plants, 
due to the presence of pyridin or similar compounds, 
yet the almost universal indorsement of soot as a ferti- 
lizer shows that the presence of poisonous substances must 
be considered as most exceptional. 

192. Light soot best. — The best soot is usually that 
which is the lightest in weight, and heavy weight indicates 
contamination with mineral matter of questionable value. 
The usual weight of a bushel of soot is about 28 pounds. 

193. Insects and cocoons. — It has been found that 
certain insects yield as much as 19 per cent of fat, and that 
in their natural state they may contain from 3.2 to 8.41 
per cent of nitrogen. In addition, the content of phos- 
phoric acid has been found to range from 0.6 to 1.5 per 
cent and the potash from 0.5 to 0.96 per cent. Certain 
of the richer of these insects, after the removal of the fat 
and complete dessication, yield a product containing as 
much as 14 per cent of nitrogen. 

The cocoons of the silk worm have been found to con- 
tain 1.82 per cent of phosphoric acid, 1.08 per cent of 
potash, and 9.42 per cent of nitrogen. 

194. Peat and muck. — Peat and muck, though con- 
taining all of the usual mineral elements of agricultural 



MISCELLANEOUS NITROGENOUS SUBSTANCES 109 

importance, nevertheless contain too little of any of them 
to be of practical significance as manures. Such vege- 
table residues are valuable as soil amendments by virtue 
of the large volume of organic matter which they contain, 
and on account of their nitrogen, although the latter is 
but very slowly available. The composition of muck and 
peat varies widely, dependent upon whether they are 
derived from trees, shrubs, grasses, mosses, or other forms 
of plant life and also according to the quantities and kinds 
of mineral matter which they contain. Air-dry peat may 
be assumed to range in nitrogen content from 1 to 2.5 
per cent, according to the materials of which it was formed. 

195. Peat and muck especially valuable on light soils. — 
Peat and muck are especially applicable for use on light, 
sandy, and gravelly soils which leach badly and lack 
vegetable matter. On such lands these materials may 
effect a veritable transformation in productiveness, es- 
pecially in seasons when the rainfall is light, or when it is 
unevenly distributed, but not always if excessively dry. 

196. Salt and fresh muds. — Dried mussel mud is 
reported by Goessmann as containing 0.72 per cent of 
nitrogen and 0.35 per cent of phosphoric acid. Another 
sample of salt mud, with 53 per cent of water and 41 per 
cent of ash ingredients, contained 0.4 per cent of nitrogen. 
Fresh-water mud, with a moisture content of 40 per cent, 
contained 1.37 per cent of nitrogen, 0.22 per cent of 
potash, and 0.26 per cent of phosphoric acid. 

None of these materials is sufficiently valuable to 
justify hauling to a considerable distance, and they are 
often chiefly of use in improving the physical condition of 
sandy or gravelly soils. 

197. Cereal and other seed by-products. — Among 
the various cereal and other seed by-products, cotton- 



110 FERTILIZERS 

seed meal is probably the most important, from the fer- 
tilizer standpoint, of any which are extensively used in 
the United States. Notwithstanding the high feeding 
value of cotton-seed meal and the wisdom from the stand- 
point of national economy of feeding it first, and of using 
the resultant dung as a manure, enormous quantities of 
it are used separately for special manurial purposes and 
also as an ingredient of ready-mixed commercial ferti- 
lizers. It is used extensively, especially in the South, not 
only as a manure for cotton and sugar cane, but also for 
other crops, and it is one of the favorite sources of organic 
nitrogen, especially for tobacco. For this latter purpose 
enormous quantities of it are used in the Connecticut 
Valley, in the states of Connecticut and Massachusetts. 

198. The composition of cotton-seed meal. — Owing 
to changes in the method of removing the oil, cotton-seed 
meal is not usually as rich in nitrogen as formerly, the 
lower limit for the decorticated meal being about 6 per 
cent, and the upper limit 7 per cent. The undecorticated 
cotton-seed meal contains about 4 per cent of nitrogen. 
In addition to nitrogen, cotton-seed meal contains about 
2.5 per cent of phosphoric acid, and about 1.7 per cent of 
potash. 

199. The composition of linseed meal. — Linseed meal 
and cake contain from 4.9 to 5.8 per cent of nitrogen, 1.2 
per cent of potash, and 1.8 per cent of phosphoric acid. 

200. The composition of malt sprouts. — Malt sprouts 
reach a limit of from 3.5 to 4 per cent of nitrogen, 2 per 
cent of potash, and 1.3 per cent of phosphoric acid. 

201. The composition of castor pomace. — Castor 
pomace contains from 5.5 to 5.75 per cent of nitrogen, 
from 0.6 to 3.4 per cent of potash, and from 1.5 to 2.25 
per cent of phosphoric acid. 



MISCELLANEOUS NITROGENOUS SUBSTANCES 111 

202. The composition of wet brewer's grains. — Wet 
brewer's grains contain 76 per cent or more of water, 1.2 
per cent of ash, 0.9 per cent of nitrogen, 0.5 per cent of 
phosphoric acid, and 0.05 per cent of potash. 

203. The composition of gluten feed. — Gluten feed 
contains usually from 4 to 5 per cent of nitrogen, but only 
0.75 per cent of ash. 

204. The utilization of the spent wash of distilleries. — 
The spent wash of distilleries of various kinds contains 
notable quantities of nitrogen. This represents a loss of 
1 to 1.25 pounds of nitrogen, per 10 gallons of 100 per cent 
alcohol produced. The wastes from the distillation of 
beet sugar, molasses, and sucrate liquors contains 1.4 
per cent of nitrogen and 0.9 per cent of salts. Attempts 
to recover these wastes by dry distillation are complicated 
by the tars and other products, difficult of purification. 
Many other methods of treating these liquors have like- 
wise been tested. 

205. The process of Vasseux. — The process of Vas- 
seux, which is employed with gratifying results in France 
and Spain, consists in concentrating the wash and adding 
sulfuric acid, whereupon the potassium sulfate crystal- 
lizes out in the mass and is separated by decantation, 
filtration, and centrifugal treatment, yielding finally a 
product containing 75 to 80 per cent of potassium sulfate. 
The drying of the liquor is completed in vacuo, where- 
upon it is poured into trucks. After cooling, this residue 
is crushed and prepared for agricultural use. The final 
product contains 6 to 7 per cent of nitrogen and 6 to 7 
per cent of potash. It is almost wholly soluble in 
water, and is said to be an excellent fertilizer. The 
usual yield is 300 pounds of fertilizer per tori of the 
molasses treated. 



112 FERTILIZERS 

206. The process of Effront. — A process devised by 
Effront consists in converting the organic nitrogen of 
these spent liquors into ammonia by the employment of 
amidase in an alkaline medium. The ferment is then 
separated for further use, and the ammonia is won by dis- 
tillation. A butyric acid ferment and others separated 
from a garden soil have been similarly employed by 
Effront in treating spent wash. By this method there was 
secured from 814 gallons of molasses, not only the cus- 
tomary 22 gallons of alcohol, but also 77 pounds of pure 
volatile fatty acids. 



CHAPTER XI 

THE AVAILABILITY OF ORGANIC NITROGEN AND FACTORS 
AFFECTING IT 

In determining the availability of organic nitrogenous 
substances, the efficiency of their nitrogen is usually com- 
pared with that in nitrate of soda, which for the sake of 
convenience is usually placed at 100. 

207. The factors of temperature and moisture. In 
such work temperature and moisture conditions, as well 
as the texture and chemical reaction of the soil, are im- 
portant factors, for it is well recognized that in warm 
climates, especially on open soils, and for plants having a 
long period of growth, comparatively inert forms of nitro- 
gen act much better than in temperate climates and on 
compact soils. 

208. Effect on the soil reaction. — It is coming to be 
more generally appreciated than formerly that soils are 
rendered less acidic or more alkaline by sodium nitrate, 
whereas certain organic nitrogenous substances may exert 
an appreciable ultimate acidic effect upon the soil by 
virtue of the nitric acid resulting in the course of their de- 
composition. 

209. Effect of large applications at the outset. In 
case a very heavy application of nitrate of soda is made 
at the outset, it may in some cases interfere, for a time, 
with the physiological functions of the plant to such an 
extent that even if it actually takes up more nitrogen, 

T 113 



114 FERTILIZERS 

the total quantity of dry matter may finally be less than 
that produced by a like amount of nitrogen in certain 
organic materials, which are more slowly available. For 
this reason deductions as to the availability of the nitro- 
gen should properly be based upon the nitrogen actually 
taken up by the plants, rather than merely upon the total 
dry matter produced. 

210. Employment of different amounts of nitrogen. — 
It is also important in making such availability tests to 
use two or three series of experiments in which different 
amounts of nitrogen are employed. 

211. Other elements must be supplied generously. — 
Care should also be taken to determine definitely by 
experiment whether enough of all the other fertilizing 
ingredients has been employed to insure that nitrogen 
is really made the factor which limits growth. The 
point just mentioned is especially important in view of 
the now well-recognized physiological and other func- 
tions, performed by sodium salts when potash is lacking, 
for if the supply of potash were insufficient, the greater 
yield produced by nitrate of soda, in comparison with 
organic nitrogen, might be due to a considerable extent 
to the soda having performed some part of some of the 
functions of potash. If this were not guarded against 
or anticipated, the conclusion might be drawn that the 
nitrogen in other materials was relatively much more in- 
ferior in comparison with that in nitrate of soda than the 
actual facts would justify. 

212. False conclusions a result of neglect of con- 
ditions. — A careful study of the literature of the subject 
reveals cases in which comparisons of nitrogenous sub- 
stances have been made in which no potassic fertilizers 
whatever were employed, nor was evidence sought to 



THE AVAILABILITY OF ORGANIC NITROGEN 115 

show that sufficient was already present in the soil to 
meet the maximum plant requirements. To this and to 
similar oversights may be attributed some part of cer- 
tain of the discrepancies concerning especially the value 
of hoof meal and horn meal, although they may also have 
been due to the different methods of preparing the ma- 
terials used by the different experimenters ; and to the 
occasional unrecognized adulteration with substances of 
highly inferior character. 

213. Results by Eckenbrecher. — A study of the effi- 
ciency of certain organic substances was made by Ecken- 
brecher, for a single season, in " sterile " sand from which, 
based upon nitrate of soda at 100, he classified the effi- 
ciency of the nitrogen in certain substances as follows : — 



Bone meal 
Horn meal 
Dried blood 
Crude guano 



Fob the Production 
of Straw 



100 
91 

86 
6 



For the Production 
of Grain 



77 

56 

65 

6 



It is evident that very different results might have been 
secured in normal soil. 

214. Results by Kellner. — It was found by Kellner, 
in the warm climate of certain parts of Japan, that organic 
nitrogen was superior to nitrogen in sulfate of ammonia, 
due, presumably, to the rapid nitrification of the former, 
and to its loss by drainage before the plants could utilize it. 

215. Results by Petermann. — Many experiments on 
the availability of organic nitrogen were made by A. Peter- 
mann in Belgium from which he concluded that nitrate 



116 FERTILIZERS 

of soda should be given the highest rank. This was fol- 
lowed in efficiency by dried blood, then by wool which 
had been treated with sulfuric acid, next by bone meal, 
then by untreated wool, and finally by leather meal. 

216. Precautions suggested by Wagner and Dorsch. — 
Extended studies of availability by Wagner and Dorsch 1 
led them to lay down the following rules for such tests : 
(1) The experiments must cover several successive years. 
The same lots of soil must also be used throughout the 
whole period, and the same fertilization must be repeated 
annually. This is to aid in arriving at any cumulative 
effect of the organic fertilizers, in contrast to the supposed 
more temporary action of the nitrogen in nitrates. Con- 
cerning this recommendation, it may be said that its im- 
portance seems to have been somewhat overestimated in 
view of the many cases on record in which but relatively 
little effect is noticed, the second year, from heavy appli- 
cations of organic nitrogen ; furthermore, the cumulative 
effect of nitrate of soda in an acid soil, due to its basic 
properties and to the possibility of its nitrogen being partly 
transformed into " humous " combinations, may also be 
much greater than is sometimes recognized. 

(2) The soil must contain sufficient lime to insure that 
there will be neither delay nor cessation of the process of 
nitrification. 

(3) In selecting the soil, one should neither use one that 
is extremely favorable as concerns its physical character, 
nor one which is exceedingly poor, but rather a soil that 
would be ranked as medium in this respect. Later, if 
desired, the results may be studied under extreme con- 
ditions. 

J Die Stickstoffdungung der Landwirtschaftlichen Kulturpflanzen, 
Erster Theil, Berlin, 1892, pp. 242-258. 



THE AVAILABILITY OF ORGANIC NITROGEN 117 



(4) One should introduce as many different organic ni- 
trogenous fertilizers into the experiment as possible, in order 
that the results with a given substance may appear in their 
proper relation to those secured with other substances. 




12 3 4 5 

Fig. 8. — Barley, "Unlimed." 
1. No nitrogen. 2. Ammonium sulfate. 3. Leather. 

4. Dried blood. 5. Nitrate of soda. Same amounts of pot- 
ash, phosphoric acid, and nitrogen used in each case. Same 
as Fig. 9, except for the omission of lime. 

(5) None of the fertilizers should be applied until spring, 
in order to avoid possible loss during the winter. 

(6) In case a substance contains some other fertilizer 
ingredients than nitrogen, care must be taken, by the addi- 
tion of an assured excess of all of them, to eliminate the 
possibility of their having influenced the result. 



118 



FERTILIZERS 



(7) All of the lots of soil must receive even slightly 
more of all the necessary fertilizers, other than nitrogen, 
than are necessary to the production of a maximum crop. 

(8) Less nitrogen should be used in all cases than is 
necessary to the production of a maximum crop, in order 
that the best forms may exert their full effect. 

(9) In order to make sure that the conditions under (7) 
and (8) have been surely met, nitrogen must be applied 
in at least two different amounts. 




12 3 4 5 6 

Fig. 9. — Barley, "Limed" (except 1). 

1. No nitrogen, no lime. 2. No nitrogen. 3. Ammonium sulfate. 
4. Leather. 5. Dried blood. 6. Nitrate of soda. All received like 
amounts of potash, phosphoric acid, and nitrogen. Like Fig. 8, excepting 
that lime was used for all but No. 1. 

(10) The nitrogen content of the soil which is selected 
should be so low that fairly large applications of nitrogen 
may be made, for the accuracy of the results will be in- 
creased thereby. 

(11) One should use relatively larger amounts of the 
less available substances than of the more active ones, in 
order that the experimental error may be made as nearly 
alike in all cases as possible. 

(12) The experiments should be conducted on land 



THE AVAILABILITY OF ORGANIC NITROGEN 119 

in its natural condition, as well as in pots ; since the former 
provides against any possible errors due to higher tem- 
peratures in the pots, and the use of the latter insures 
against losses by drainage. 

217 Results of tests by Wagner and Dorsch. — Ine 
experiments by Wagner and Dorsch were conducted with 
due recognition of the foregoing precautions, including 
tests in pots and in soil in its natural location. These 
experimenters call attention to the variation in the 
chemical and physical character of such nitrogenous 
materials from time to time; also to the wide variations 
in soil temperature, moisture content, and other factors 
that may modify results. Finally, as representative 
average figures expressive of the efficiency of the nitrogen 
in various materials, based upon nitrate of soda at 100, 
they give the following : — 

Relative Value 

Nitrogen in nitrate of soda „„ 

Nitrogen in sulfate of ammonia •••;•/; 
Nitrogen in dried blood, horn meal, and green (not 

yet woody) plant substance • •"• 

Nitrogen in fine ground bone meal, meat meal (azo- 

tin), and dry ground fish Jj" 

Nitrogen in stable manure ^ 

Nitrogen in wool waste j*" 

Nitrogen in leather meal 

218. Results by Wheeler and Hartwell. — In experi- 
ments by Wheeler and Hartwell made in " Miami " silt 
loam, in deep pots set in the ground so as to make the 
interior and exterior soil level, sulfate of ammonia was 
found to be highly toxic, if employed without lime, but 
when used with lime its efficiency rose to 92 on the basis 
of 100 for the nitrogen in nitrate of soda. Similarly, on 
the unlimed soil the efficiency of the nitrogen in dried 
blood was but 45.5 on the same basis, whereas after liming 



120 FERTILIZERS 

it was 90.3. Steamed, ground leather had an efficiency 
on the unlimed soil of but 0.9 ; but after liming the effi- 
ciency rose to 13.8, or to essentially the same figure noted 
by Wagner in many of his individual experiments. 

219. Results by Voorhees. — In a series of experi- 
ments by Voorhees at the New Jersey experiment station 
it was found that the nitrogen of nitrate of soda was more 
available than that in any other materials. It was also 
found, when nitrate of soda was employed, that the crop 
was able to secure even a larger proportion of the soluble 
nitrogen derived from the soil and from the manures which 
had been added to it, than when no nitrate was used. 
Placing the value of the nitrogen in nitrate of soda at 100, 
the following seasonal variations in the efficiency of the 
nitrogen in other substances were observed by Voorhees : 
the value of the sulfate of ammonia was 99.5 in the year 
1898, 77.9 in 1899, and 87.8 in 1900. The corresponding 
values found for dried blood in the three years were, respec- 
tively, 95.4, 61.3, and 73.1. 

It was also shown by Voorhees that the soluble nitrogen 
in liquid manure possesses a high value. The insoluble 
nitrogen in fresh and leached barn-yard manures was 
found to become gradually soluble ; and its value was much 
greater as the length of the period of growth was in- 
creased. 

Views of Lawes. — In the climate of England, Lawes 
considered the nitrogen of shoddy and of most other or- 
ganic substances as being only from one-half to two-thirds 
as efficient as that in nitrate of soda, sulfate of ammonia, 
and guano. 

220. Results by Kellner on wet soil. — It has been 
shown by Kellner that in the wet rice fields of Japan am- 
monia, instead of nitrates, is formed from organic nitrog- 



THE AVAILABILITY OF ORGANIC NITROGEN 121 

enous substances. In his experiments with rice he used 
in one series twice as much nitrogen as in the other, and in 
both cases liberal quantities of phosphoric acid and potash. 
The applications were also made some days in advance of 
the setting of the rice plants in order to avoid toxic effects 
from a too rapid formation of ammonia at the outset. 
The natural soil, when air-dried, contained 0.61 per cent 
of nitrogen. Under such circumstances, in the warm 
climate which prevailed, the relative efficiency of the vari- 
ous materials, based upon the mean of the gain in crop, and 
of the nitrogen recovered, was found to be as follows : — 

Relative Efficiency 

No manure 

Sulfate of ammonia 100 

Bone meal, steamed 142 

Fish-scrap, 9.9 per cent of nitrogen 135 

Fish-scrap, 9.5 per cent of nitrogen 133 

Blood meal 130 

Bone meal, raw 120 

Distillery slop, dried 118 

Horn meal • 116 

Peruvian guano 116 

Press cake 104 

Rape cake 106 

Night soil 106 

Farm manure 88 

Rice husks 48 

Green plants 42 

Owing to the fact that irrigation waters were used on 
the lands where the foregoing tests were made, the mate- 
rials containing nitrogen which was wholly or partly sol- 
uble were at a great disadvantage, as compared with the 
materials from which the nitrogen could not be so readily 
dissolved and carried away. This applies particularly 
to the sulfate of ammonia, farm-yard manure, night soil, 
guano, and materials of similar character. It is obvious, 
therefore, that the figures in the preceding table are ap- 



122 FERTILIZERS 

plicable only to similar conditions and not to those usually 
existent on farm lands. 

221. Results by Seyffert. — In experiments by Seyf- 
fert with kohl-rabi, in which identical amounts of nitrogen 
were used in all cases, in the various materials, the fol- 
lowing results were secured : — 

Grams of Crop 

No nitrogenous fertilizer 76 

Crude Mejillones guano 71 

Leather meal, steamed 469 

Steamed bone meal 1572 

Dried blood 1654 

Horn meal, steamed 2005 

Nitrate of soda 2608 

222. Results by Heinrich. — Experiments are on record 
by Heinrich in which he found, with oats, that there was 
no material difference in the efficiency of the nitrogen in 
leather meal and in blood meal. This result is, however, 
so completely out of accord with the experience of other 
experimenters that serious doubt is cast upon the genuine- 
ness of the blood meal, or upon the suitableness of the con- 
ditions under which the experiment was conducted, or 
possibly upon the interpretation of the experimental 
data. 

223. Results by Johnson. — According to S. W. John- 
son's experiments with Indian corn, certain organic nitrog- 
enous fertilizers should be rated in efficiency as follows : — 

Nitrate of soda 100 

Castor pomace (best results) 85 

Linseed meal 80 

Dried blood 77 - 

Cotton-seed meal 76 

Castor pomace (poorest results) 74 

Hoof and horn meal 72 

Dried fish 70 

Tankage 68 



THE AVAILABILITY OF ORGANIC NITROGEN 123 

224. Results by the nitrification method of Muntz and 
Girard. — Experiments were made by A. Muntz and 
Girard to determine the relative value of nitrogenous 
fertilizers by subjecting them to nitrification and measur- 
ing the amount of nitrates produced at the end of 30 and 
39 days. This resulted in showing that the nitrogen in 
sulfate of ammonia should be ranked ahead of that in 
organic compounds. This was followed in order by the 
nitrogen of guano, bat manure, leguminous plants used as 
green manure, dried blood, meat meal, horn meal, and 
roasted horn. Roasted leather was found to nitrify very 
slowly, and raw leather not to any practical extent. 

225. The pepsin method. — Many investigators in the 
United States and in Europe have studied the solvent 
action of pepsin solution upon various organic nitrogenous 
substances as a means of determining their crop-producing 
value. The results in many cases accord fairly well with 
those secured in tests with plants, though certain gross 
disagreements have been noted. It was found in the 
course of this work that a preliminary treatment of the 
material with borax increased the solvent action of the 
pepsin. 

226. The permanganate method. — In the hope of 
finding some more reliable chemical method than that 
afforded by treatment with pepsin, many experiments with 
potassium permanganate have been made in acid, neutral, 
and alkaline solutions. Recently the agricultural experi- 
ment stations of New England, New York, and New 
Jersey have adopted, tentatively, the treatment with an 
alkaline solution of potassium permanganate, for the pur- 
pose of furnishing evidence as to the probable efficiency of 
the insoluble organic nitrogen in ready-mixed commercial 
fertilizers. The organic residues, remaining after extract- 



124 FERTILIZERS 

ing the fertilizers with water, are being tested, by way of 
pot experiments with plants, in order to ascertain how 
far this chemical method of treatment is in accord with 
the degree of availability shown by plants in normal soil. 
227. Lipman's ammonification method. — Recently 
Lipman l and others have suggested the determination of 
the availability of organic nitrogen by the rate at which 
ammonification occurs, under definite conditions. Ac- 
cording to Lipman, the results by this method agree suffi- 
ciently well with those secured in vegetation experiments 
with plants, to justify its employment in many cases. 
Attention is called to the fact that the rate of ammoni- 
fication is affected by the carbohydrate content of the 
soil and by other factors. 

1 Centralb. f. Bakt., 31 (1911), 49-85. 



CHAPTER XII 

CALCIUM AND POTASSIUM NITRATES 

Calcium nitrate and potassium nitrate are two espe- 
cially useful sources of nitrogen which will be considered 
in detail. 

228. Calcium nitrate a new fertilizer. — Calcium ni- 
trate is a comparatively new product in so far as concerns 
its production and use for agricultural purposes, and it is 
but just being introduced into this country in an experi- 
mental way, though it has been used to some extent in 
Europe for a very short time. This nitrate has been long 
and favorably known as one of the important compounds 
formed in soils in connection with the usual processes of 
nitrification. 

229. Production possible due to cheap electricity. — 
Recently, due to the great developments in the line of 
cheapening the cost of electricity, it has become possible, 
by employing an electric arc furnace, to oxidize the nitro- 
gen of the air to nitrous oxid and nitric oxid. In fact, in 
1898 Sir William Crookes predicted that the world's supply 
of nitrogen would soon come from the air. He pointed 
out that all that was needed was some means of maintain- 
ing the energy necessary to cause the continuous union 
of oxygen and nitrogen on a sufficiently large scale. Based 
upon the work of Lord Raleigh, he further expressed the 
belief that with the perfection of the electrical plant at 
Niagara Falls this would be accomplished. 

125 



120 FERTILIZERS 

230. The work of Lovejoy and Bradley. — Soon there- 
after Lovejoy and Bradley, by producing several arcs 
between platinum poles with a continuous current of 10,000 
volts, generated oxicl of nitrogen which was converted 
into a mixture of sodium nitrite and sodium nitrate. This 
process proved, however, too destructive to the apparatus 
to be remunerative. 

231. The process of Birkeland and Eyde. — The later 
process developed successfully by Birkeland and Eyde 
involves the use of an alternating current of not more than 
about 5000 volts. An arc is formed between U-shaped 
copper electrodes cooled from within by a current of water. 
The arrangement of the two hollow electrodes is such as 
to produce a flat and broad flame, the temperature of which, 
though only 2600° C, is not so luminous as might be 
expected. The flaming electrical arc is moved backward 
and forward by a magnet in such a way as to produce a 
maximum of contact and consequent oxidation. About 
2694 cubic feet of air are passed through the furnace, 
per minute, where it is subjected to an alternating current 
of from 3000 to 4000 volts, giving a flame 6 feet in 
diameter. When the air emerges, its temperature is from 
600° to 700° C. It then carries about 1 per cent of nitric 
oxid and is next passed through a steam boiler in order 
that it may give up a part of its heat, in the generation 
of steam. The current is then passed through two oxidiz- 
ing chambers. Here it takes on oxygen from the air, 
after which it is passed through five condensing towers, 
each of which is about 50 feet high. In the meantime, 
water is allowed to trickle down the broken quartz with 
which four of the towers are filled ; and by the time it has 
reached the bottom of the fourth, it contains approxi- 
mately 5 per cent of nitric acid. This solution is then passed 



CALCIUM AND POTASSIUM NITRATES 127 

down the third, second, and first towers successively, and, 
upon reaching the bottom of the last of these, it contains 
50 per cent of nitric acid. From here it passes to a fifth 
tower, which contains milk of lime, and, finally, to a sixth 
tower, which carries beds of lime. In this last tower the 
solution is absorbed, and there is formed a mixture of 
calcium nitrite and of calcium nitrate. This product 
upon treatment with some of the nitric acid is all changed 
into nitrate, and the nitrous fumes which result are led 
back to the oxidizing chamber. The final product, after 
concentration, is poured, in a molten condition, into can- 
isters for shipment. 

232. First product too hygroscopic. — The crystallized 
nitrate of lime which was produced at first was so hy- 
groscopic that it would melt if held in the hand, and it 
became necessary to mix it with peat dust before its ap- 
plication to the soil. 

233. Processes for lessening hygroscopic tendency. 
Later attempts have been made to make a basic nitrate 
of lime, but this contained only 11.7 per cent of nitrogen, 
and hence increased to a serious extent the cost of trans- 
portation per unit of nitrogen. Subsequently a partially 
dehydrated salt was produced containing 13 per cent of 
nitrogen. 

In order to obviate the tendency of nitrate of lime to 
deliquesce, it has been mixed at times with alkaline sul- 
fates, with sulfate of potash, sulfate of magnesia, and with 
calcined kieserite. By such treatment a powder is formed 
which is said to afford no more difficulty, in this particular 
respect, than is met with in the handling of nitrate of soda. 

234. Chemical composition. — The solidified or pow- 
dered product of calcium nitrate contains about 25 per cent 
of lime in an unchanged condition. It also contains 13 



128 FERTILIZERS 

per cent of nitrogen, which is equivalent to 75 per cent of 
calcium nitrate. 

235. Calcium nitrate as a fertilizer. — The chief draw- 
back to the practical use of calcium nitrate as a fertilizer 
has been its tendency to deliquesce readily, especially in 
a moist climate. 

Since calcium nitrate carries an excess of lime, it is an 
ideal source of nitrogen for certain of the granitic, gneissic, 
slate, shale, and sandstone soils, many of which are often 
practically devoid of carbonate of lime ; but on calcareous 
soils, and for plants that do not respond favorably to lim- 
ing, it may be much less valuable. The tendency of cal- 
cium nitrate is the direct opposite of that of sulfate of 
ammonia, for the latter rapidly exhausts the calcium car- 
bonate supply of the soil. In actual practice the results 
secured with calcium nitrate appear to lack more or less 
in agreement. This is doubtless due to the fact that suffi- 
cient attention has not always been paid to the quite dif- 
ferent character of the soils under experiment, and to the 
widely varying effect of lime upon the growth of the differ- 
ent varieties of plants, for which it has been used. In 
general, however, the results from the use of calcium ni- 
trate have been highly favorable, agreeing well with those 
secured with nitrate of soda. 

236. Danger of the earlier products injuring horses 
and workmen. — Attempts to sow calcium nitrate broad- 
cast by itself are said to be likely to result in serious injury 
to the hands and eyes of the workmen. If one attempts 
to use a machine, such as is ordinarily employed for dis- 
tributing fertilizers, it flows too freely to admit of its uni- 
form and satisfactory distribution. On this account it 
has been suggested that the material be mixed with soil or 
with some other suitable dry substances before its dis- 



CALCIUM AND POTASSIUM NITRATES 129 

tribution. It has been used mixed with calcium cyanamid 
with better results than when the cyanamid is used alone. 

237. Extent of the output of calcium nitrate. — In the 
first three months of 1908 the output of the Norwegian 
Hydro-electric Nitrogen Works of Christiana was 1059 
tons of calcium nitrate ; or more than in the entire previ- 
ous year. Since that time other plants have also begun 
operations. In April, 1911, it was reported that the total 
available output until August of that year was already 
sold ; and that, with the completion of the new works then 
under construction, it was expected that the annual pro- 
duction would reach 100,000 tons. 

238. Cost of producing calcium nitrate. — The present 
price of calcium nitrate is based upon that of nitrogen in 
nitrate of soda, on which basis it can be produced at a good 
profit. In fact, it has been claimed that with the present 
cheap electric current, generated in Norway, calcium ni- 
trate can be manufactured at a price 30 per cent cheaper, 
per unit of nitrogen, than the present ruling price of nitro- 
gen in nitrate of soda. 

239. Other processes. — Other modified processes for 
the manufacture of calcium nitrate have been devised by 
E. Rossi, in Italy, and by G. Erlwein, who is in the em- 
ploy of the firm of Siemens & Halske, in Germany. 

240. Sources of potassium nitrate. — Impure potassium 
nitrate, known commercially as " niter " or " saltpeter," 
is found naturally in certain parts of India, also near 
Mabelstadt and Peliska in Cape Colony, South Africa, 
and in other countries, where it appears as a white incrus- 
tation on the surface of the soil. It is also often found 
mixed with the soil to a considerable depth. 

The nitrate is extracted from the earthy matter by 
water. The solution is then evaporated by exposure to 



130 FERTILIZERS 

the rays of the sun, or by artificial heating, after which it 
is allowed to stand and crystallize. In this crude or par- 
tially purified condition it is known as " grough," and it 
usually contains about 44 per cent of potassium oxid and 
11 per cent of nitrogen. There is frequently associated 
with the potassium nitrate from 1 to 10 per cent of im- 
purities, chief among which are sodium chlorid and sul- 
fates of soda, potash, and lime. 

241. Artificial niter beds. — Potassium nitrate has also 
been prepared at times in artificial niter heaps or beds. 
Such heaps are prepared under a shelter, where there is an 
impervious floor to prevent the escape of liquids. The 
side of the heap most exposed to evaporation is often kept 
vertical, whereas the other side is built up in the shape of 
successive grooved terraces upon which the drainage from 
stables is occasionally conducted. In this way the fer- 
mentation of the vegetable and animal matter, which is 
mixed with limestone, old mortar, wood-ashes, or similar 
basic material, is readily promoted. The nitrates which 
are formed are finally leached to the vertical side of the 
heap, where they accumulate as an efflorescence, due to the 
continual evaporation at that point. When the accumu- 
lation has become great enough to justify it, the outside 
vertical layer and the nitrate accumulated on its face are 
removed. The material is next extracted with water and 
is still further purified by crystallization. The residual 
matter, after its extraction, is returned to the terraces on 
the rear of the heap. Usually the heaps are torn up and 
rebuilt after from two to three years. 

A temperature of from 60° to 70° F. is considered favor- 
able to the nitrifying processes, though, as is well known, the 
optimum temperature for nitrification is probably about 
98° F, 



CALCIUM AND POTASSIUM NITRATES 131 

There was long much mystery about the cause and the 
nature of the changes actually taking place in such beds, 
but this has been removed by the work of Frankland, 
Warrington, Winograclsky, and others, who have shown 
that the changes are the result of the activity of certain 
species of microorganisms. 

The chief nitrates associated with the potassium nitrate 
from such artificial beds are nitrates of lime, magnesia, 
and ammonia. These may all be converted into potas- 
sium nitrate, however, by treatment with potassium 
carbonate. 

242. Made for industrial purposes from nitrate of soda. 
— For industrial purposes, potassium nitrate is manufac- 
tured from the Chilian nitrate of soda and potassium 
chlorid. 

243. Potassium nitrate often economical for agricul- 
tural use. — It is usually asserted that, potassium nitrate, 
on account of its high price, finds little or no application 
in agriculture, excepting in a small way in certain special 
garden fertilizers, and that the elements which it fur- 
nishes can be secured more cheaply in nitrate of soda and 
in muriate of potash. Nevertheless, it has often happened 
in recent years in the United States that niter has been the 
most economical source of potash and nitrogen on the 
Atlantic seaboard, and at points where the transportation 
charges on fertilizers are still greater, it may frequently 
be found economical for agricultural uses. 

244. Chlorin avoided by using potassium nitrate. — 
Potassium nitrate is especially applicable wherever large 
amounts of chlorin are objectionable; as, for example, for 
tobacco, sugar beets, and for certain other field crops, 
but more particularly in greenhouses, where toxic residues 
should be especially avoided. 



CHAPTER XIII 

NITRATE OF SODA 

The most widely used and known of all nitrate fertilizers 
is nitrate of soda, which, owing to its vast agricultural im- 
portance, will be discussed in its various relationships to 
plants and soils. 

245. Sources of nitrate of soda. — Quantities of nitrate 
of soda of economic importance occur in Egypt, and minor 
deposits also in the pampas of Peru, Chili, and Bolivia. 
The chief deposits in the world are found in the plateau of 
Tarapaca in northern Chili (formerly Peruvian territory), 
and in the desert of Atacama. This plateau, which is 
merely an elevated sea bed, is now from three to four 
thousand feet above the level of the ocean. It extends 
for approximately seventy-five miles north and south, and 
from twenty to twenty-five miles from east to west. The 
plateau where the nitrate is most abundant is shut in by the 
Cordilleras on the east and by a low range of foothills on 
the west. Rain seldom falls there more frequently than 
every two to three years, and then in such small quanti- 
ties that it evaporates quickly. Immediately on the sur- 
face of this plateau is found a rock known as " costra," 
carrying occasionally small amounts of phosphates, but 
consisting chiefly of sand and gypsum. Beneath this lies 
the " congels," a conglomerate rock composed of gravel 
and clay. Underneath the whole lies the " caliche " or 
impure nitrate of soda associated with earthy matter and 

132 



NITRATE OF SODA 133 

with salts of calcium, magnesium, and potassium. The 
overlying rocks range usually from three to ten feet or 
more in depth, while the caliche may vary in depth from a 
few inches to from 8 to 10 feet. Its average depth is 
about 3 feet. 

246. Concerning the origin of the Chilian nitrate of 
soda. — Several theories have been advanced to explain 
the mode of origin of the nitrate. (1) It has been suggested 
that the nitrates have resulted from natural electrical 
discharges by which the nitrogen of the air has been fixed, 
resulting in the final formation of nitrates. The sugges- 
tion has also been made that the carbonates of the alkalies 
and of the alkaline earths have aided in the oxidation of 
the atmospheric nitrogen. 

(2) That the nitrate was formed from guano deposits, 
which upon nitrification yielded calcium nitrate. The 
calcium nitrate is believed to have then reacted with 
sodium chlorid and with other sodium salts of some in- 
land salt lake by a process of change analogous to one 
said to be taking place at the present time in Hungary. 
By the reactions suggested, sodium nitrate is supposed 
to have been produced. The resulting calcium chlorid is 
believed to have been largely removed in solution. This 
view of the origin of the beds is supported also in some 
measure by the presence of sodium chlorid in the caliche. 
The lack of considerable amounts of phosphate, associated 
with the deposit, is, however, considered as an objection to 
this theory. 

(3) That in the elevation of the plain from the bed of 
the ocean great numbers of marine animals and vast quan- 
tities of the great sea-weeds, which are common on the 
Pacific coast of North and South America, were raised to 
a position where their decomposition and ultimate nitri- 



134 FERTILIZERS 

fication took place readily. The small amounts of phos- 
phates in the overlying rocks have been considered as 
supporting evidence of this origin, and likewise also the 
presence of iodates in the caliche. It is inconceivable, 
however, that the volume of sea-weed could have been 
sufficient to supply all of the vast quantity of nitro- 
gen ; and, furthermore, the absence of bromin, which is 
a constituent of sea-weeds, is a serious blow to this 
theory. 

(4) It is more probable for many reasons that the ni- 
trates had their origin in the higher mountain ranges, per- 
haps chiefly at a much earlier time when the rainfall was 
more abundant, and that the evaporation of these saline 
waters, due to progressive desiccation, gave rise to the 
present deposits. It remains, however, to be explained 
by this theory, from what source the iodin was derived. 
This idea of the origin of the nitrates is upheld by A. D. 
Hall, whereas another recent English writer adheres to the 
idea of their having been formed from sea-weeds. 

Recent investigations by Headden and Sackett 1 as to 
the cause of the excessive accumulations of nitrates, which 
are found to be highly destructive to apple orchards and 
to some farm crops in certain sections of Colorado, have 
shown that nitrogen is fixed from the air in great quantities, 
chiefly by Azotobacter chroococcum. The extent of fixa- 
tion in a sample of soil from the Colorado college farm, in 
the course of a period of incubation extending over 27 
days, is said to have been equal to 5222 pounds of nitrogen, 
or to 17.5 tons of " proteids " per acre-foot of soil, per 
annum. If the rate of increase of nitrate nitrogen ob- 
served by Headden, for a period of 48 days, were main- 

1 Buls. 178 and 179, respectively, Agr. Expt. Sta., Colorado Agricul- 
tural College. 



NITRATE OF SODA 135 

tained continuously for a year, it would amount to four 
and one-third tons of nitrates per acre-foot of soil. In a 
later article 1 Headden states that " The area in which the 
nitrogen fixation by the Azotobacter is actually taking place 
in Colorado under our semi-arid conditions is sufficiently 
extensive to entitle the suggestion, that the nitrogen pres- 
ent in the Chili-saltpeter was also fixed by Azotobacter, to 
serious consideration." Hilgard also calls attention to the 
great quantities of nitrates in certain of the soils of Cali- 
fornia; and in one locality, over an area of ten acres, 
they were found at the rate of 1200 pounds per acre, the 
maximum being two tons per acre. 

(5) It has been pointed out recently by Kuntze that the 
vicunas and llamas are now known to have roamed in 
immense numbers, probably since time immemorial, over 
that part of the Andes where the nitrate deposits occur, 
and the fact that they always deposit their dung in the 
same place points to such accumulations as a possible 
source of the nitrates. The common salt is accounted for, 
according to this theory, as coming from the urine and 
excrement, and from the alkaline salts resulting from rock 
decomposition. This theory does not, however, account 
for the iodin which has long been one of the chief supports 
of the sea-weed theory of the origin of the nitrate. 

It appears quite possible that two or three of these dif- 
ferent sources may have contributed to the deposits. 

247. The first exploitation of the nitrate of soda. — 
Notwithstanding that the existence of the nitrate fields 
had been known since a much earlier date, the first ship- 
ments of nitrate of soda were not made from Iquique 
until 1830. These amounted to 800 tons. In the next 
ten years the annual output had risen to 10,000 tons, and 

1 Proceedings of the Colorado Scientific Society, 10 (1911), 120. 



136 FERTILIZERS 

in 1907 it amounted to 1,660,000 tons, and it has since been 
rapidly increasing. 

248. Chemical composition and purification of the 
nitrate of soda. — The crude caliche contains only from 17 
to 60 per cent of nitrate of soda. The native material is 
removed from its beds by the use of dynamite. It is then 
freed from the associated earthy matter by dissolving in 
hot water, after which it is allowed to crystallize out in 
tanks. The crystals are then removed, dried, and bagged 
ready for shipment. The mother liquors are subsequently 
utilized for the recovery of iodin compounds and certain 
other valuable salts. In its commercial state, nitrate of 
soda contains from 95 to 97 per cent of nitrate, or from 
15 to 16 per cent of nitrogen, which is equivalent to 18 
to 19 per cent of ammonia. Pure nitrate of soda contains 
16.47 per cent of nitrogen, equivalent to 20 per cent of 
ammonia, but this is too costly for agricultural uses. 

249. Impurities in nitrate of soda. — The impurities 
present in the commercial nitrate of soda employed for 
agricultural purposes are 2 to 3 per cent of water, 0.5 to 
1.5 per cent of sodium chlorid, small amounts of sodium 
sulfate, potassium sulfate, and calcium sulfate ; also so- 
dium iodate and traces of other less important salts. Some- 
times even potassium nitrate may occur as an impurity in 
nitrate of soda, though it is usually very largely removed 
in the mother liquors. The only impurity that is trouble- 
some agriculturally is sodium perchlorate, which has some- 
times been found in quantities equal to from 6 to 7 per 
cent. Amounts in excess of 1 per cent have been found to 
be harmful to crops, causing, in the case of cereals, a pe- 
culiar twisting of the leaves and poor development of the 
stalk which does not occur under normal conditions. In 
recent years, due doubtless to greater precautions in the 



NITRATE OF SODA 137 

course of the purification, few, if any, complaints of injury 
due to the presence of perchlorate have been heard. 

It is only in the rarest instances that adulteration of 
nitrate of soda has been met with, a fact doubtless due to 
vigilant inspection, and to the ease with which foreign 
materials can be recognized by chemical and other means. 

250. Physical characteristics of nitrate of soda. — The 
color of the commercial nitrate of soda ranges from brown 
and pink to grayish white. It becomes lumpy as a result 
of storage, and for this reason it is often reground when 
sold for the home-mixing of fertilizers. It is important 
to store nitrate of soda in a reasonably dry location, or it 
will readily liquefy to some extent by the absorption of 
water from the air. 

251. The availability of nitrate of soda as plant food. — 
Nitrate of soda ranks with potassium nitrate and calcium 
nitrate as one of the most efficient of all nitrogenous fer- 
tilizers, for it can be utilized by plants at once without 
the necessity of undergoing preparatory fermentative 
changes. 

252. Quantities to apply and care in using. — Nitrate 
of soda is applied in quantities ranging usually from 100 
to 400 pounds per acre, though as high as 600 to 800 pounds 
are sometimes employed for special purposes. 

Great care must be taken, in top-dressing spring grains, 
grass fields, and lawns, to apply the nitrate of soda when the 
grass is dry, for otherwise the tips of the leaves may be 
severely burned. Bags of the material should not be left 
standing on moist lawns or meadows, or the grass under- 
neath will be likely to be killed. Owing to its destructive 
power, particular attention must be paid to keeping nitrate 
of soda away from immediate contact with the seed. 

In connection with spring top-dressing, it is important 



138 



FERTILIZERS 




NITRATE OF SODA 139 

to bear in mind that if nitrate of soda is applied early, it 
tends to promote tillering and hence increases the number 
of stalks of grass and of cereals, sometimes, in the latter 
case, even at the expense of the yield of grain. If, on the 
contrary, the application is delayed until the tillering is 
complete, it merely aids in the development of the stalks 
already in existence. It is usually desirable to top-dress 
grass at an early date in the spring, not only to promote 
tillering, but also in order to push the growth as much as 
possible while abundant water is still present in the soil. 

253. Nitrate of soda corrects soil acidity. — It is a well- 
established fact that the use of nitrate of soda may gradu- 
ally improve the condition of certain acid soils which are 
naturally deficient in carbonate of lime, whereas sulfate 
of ammonia may render their condition far worse. This 
fact was strikingly demonstrated at the Rhode Island 
experiment station in the years from 1891 to 1900. Later 
also a similar result followed the use of a mixture of am- 
monium sulfate and ammonium chlorid, by Voelcker, at 
Woburn, England. In fact, in 1881 Adolf Mayer, 1 in 
classifying various agricultural chemicals, referred to 
nitrate of soda as being " physiologically basic." This 
was on account of the fact that the acid is utilized by plants 
to a greater extent than the sodium, in consequence of 
which the latter is transformed, in the soil, into sodium 
carbonate. 

254. Physical effects of the residue from nitrate of 
soda. — The residual sodium carbonate from nitrate of 
soda may result injuriously or beneficially, according to 
the character of the soil. It is well known, for example, 
that on heavy clay soils, especially if deficient in vegetable 
matter, the continued employment of nitrate of soda may 

x Landw. Vcrs.-Sta., 26, 94, 95. 



140 FERTILIZERS 

give rise to so much sodium carbonate as to seriously 
deflocculate the clay, by which its tendency to bake is 
enormously increased. The ability of such soils to admit 
air, and to absorb and deliver water to the plant in proper 
amounts, is also greatly impaired thereby. In such cases 
liming has not always been found to be an effective rem- 
edy, and it has been recommended to use acidic fertilizers, 
such as acid phosphate, sulfate of ammonia, and muriate 
of potash, which are said to correct the condition satis- 
factorily. 

255. The residual soda may liberate potash. — Atten- 
tion has been called by Hall and others to the action of the 
soda of the nitrate of soda as a liberator of potash in soils, 
whereby the arising of potash deficiencies may be delayed 
for several seasons. 

256. Residual soda can replace potash in part. — 
Several years ago, also, Paul Wagner in Germany and 
Atterberg in Sweden called attention to the fact that soda 
could probably replace potash to a certain extent, in which 
case it might be expected to act as a conserver of the 
potash supply in the soil. This idea is also supported by 
experiments at the Rhode Island agricultural experiment 
station. In one instance sodium carbonate, as well as 
sodium chlorid, more than doubled a crop of mangel 
wurzels when as much as 330 pounds per acre of muriate 
of potash, or its equivalent of potassium carbonate, had 
been added in the fertilizer. In the case of certain other 
crops which do not take up large amounts of soda under 
any circumstances, the benefit from using extra sodium 
salts was small, and yet further applications of potassium 
salts were beneficial. It was evident, therefore, that the 
soda in some cases had been chiefly helpful in some other 
way than as a liberator of potash. 



NITBATE OF SODA 141 

The idea that soda is able to perform certain functions, 
or at least a part of certain functions, in plants, which 
would be performed by potash if a sufficient supply of 
the latter were available, was also observed at the same 
station. This was shown by water-culture experiments 
in which the possibility of indirect manurial action, through 
the liberation of potash, was not only eliminated, but also 
any effect of increased osmotic pressure, and of other 
factors which might possibly exert an influence upon 
plant growth. 

257. The soda of nitrate of soda may in certain cases 
conserve the soil potash. — Many analytical data secured 
in Rhode Island with field crops, grown by the use of 
varying amounts of sodium and potassium salts, showed 
that at least certain of the " root " crops may take up far 
more soda and potash than seem strictly essential to bring 
about a given crop yield. If soda is absent, this over- 
loading of the plant with alkali is at the expense of the 
potash supply of the soil. If soda is used in the fertilizers; 
this " hunger " for alkali is partially satisfied with soda, 
and the potash supply of the soil is consequently con- 
served for future crops. It seems probable that some 
writers have paid too little attention to this feature. They 
have consequently attributed the indirect effect of the 
nitrate of soda too largely to liberation of potash from 
zeolitic combinations in the soil. 

258. Soil improvement by using nitrate of soda. — A 
striking instance of soil improvement as a result of the use 
of nitrate of soda is afforded at the Rhode Island experi- 
ment station, where it has been used continuously from 
1893 to 1912. At the outset the soil was so deficient in 
carbonate of lime that only an occasional clover plant 
could withstand the existing conditions. The lack of 



142 FERTILIZERS 

available basic substances was in fact so great that a 
single moderate application of sulfate of ammonia, on a 
neighboring plot of land, proved immediately toxic. Not- 
withstanding this, by the long-continued use of nitrate 
of soda, even without the aid of lime, the productiveness * 
of the soil for most agricultural plants has shown marked 
improvement, and the successful cultivation of clover 
on the land has been rendered more nearly possible. 
In fact, the present conditions are but little, if at all, in- 
ferior, for most varieties of plants, to those where sulfate 
of ammonia has replaced the annual applications of nitrate 
of soda and where several heavy applications of lime have 
been made in the period of nineteen years. It is evident, 
therefore, that nitrate of soda has a decided basic effect ; 
and on an acid soil, of a physical character not readily 
injured by deflocculation, it may readily bring about 
long-enduring and marked improvement in crops. 

259. Nitrate of soda may injure certain soils. — It 
must be obvious that in arid or semi-arid regions where 
the soil is sufficiently basic, or is already unduly so, nitrate 
of soda, if used continuously, might soon magnify the con- 
dition to a limit of danger, especially to all of those crops 
which are highly sensitive to basic conditions. 

From what has preceded it is evident that no general 
rule for the use of nitrate of soda can be formulated which 
is applicable to all classes of soils, for one must take into 
account their physical and chemical character as well as 
the peculiar adaptations of the individual plants to be 
grown. 

260. Benefit not due solely to hygroscopic effects. — 
It appears probable that much of the benefit from the 
use of nitrate of soda, which was formerly attributed to 
its increasing the hygroscopic character of the soil, may 



NITRATE OF SODA 143 

have been due to certain of the beneficial effects which 
have just been discussed, but which were formerly un- 
recognized or but little understood. 

261. The soda as a carrier of phosphoric acid into 
plants. — It has been found at the Rhode Island experi- 
ment station that the use of common salt or sodium car- 
bonate in fertilizers tends to an increase in the phosphorus 
content of certain root crops ; and since sodium carbonate 
is formed in the soil in consequence of the employment of 
nitrate of soda, the use of the nitrate must eventually 
result in the same effect. Such benefit is, however, not 
confined to root crops, for in experiments with cereals 
Wagner and Dorsch x find support for the experiments by 
Emmerling, Loges, Beseler, and Maercker, to the effect 
that by the use of nitrate of soda there resulted a larger 
yield, with more economical utilization of both phosphoric 
acid and potash, than when nitrate was not employed. 

262. Nitrate of soda conserves the lime supply of the 
soil. — In the examination of drainage waters at the 
Rothamsted experiment station it was found, in the case 
of some of the plots in Broadbalk field, that the applica- 
tion of nitrate of soda had lessened the annual loss of 
carbonate of lime by from 200 to 300 pounds per annum. 

263, Nitrate of soda not a stimulant. — Nitrate of 
soda is often referred to as a plant stimulant, or, in other 
words, according to the definition of one of the leading 
authorities, as something "Producing increased vital 
action in the organism at any of its parts." The term 
"stimulant" should, however, preferably be applied to that 
which acts in the manner described, but which does not 
enter into and form an essential part of the organism itself, 
and which is normally foreign to it. It is obvious that 

» Die Stickstoffdiingung der Landw. Kulturpflanzen, Berlin, 1892. 



144 FERTILIZERS 

nitrate of soda is not a stimulant in this latter sense, and 
that all of the elements absolutely essential to plant 
growth might with equal propriety be called stimulants. 
For example, a plant reared in a medium free from iron 
soon becomes chlorotic, but recovers almost immediately 
upon its application to the nutrient medium. In fact, 
the recovery is essentially as quick as that of plants when 
supplied with nitrates, in cases where available nitrogen 
is greatly needed. It is indeed a misfortune, because of 
the quick action of certain fertilizers, that the term "stimu- 
lant" should ever have been applied to them, for they ac- 
tually yield to the plant essential elements of plant food. 
As concerns the public, the designation of certain plant 
food ingredients as stimulants tends to create an unwar- 
ranted prejudice against them, and the farmer is falsely 
led to believe that, following their first beneficial effect, 
conditions unfavorable to his crop are likely to arise. 

Much of the former prejudice against nitrates, on the 
ground that they are stimulants, has doubtless arisen 
from observing the frequent temporary benefit from their 
use when unaccompanied by the other ingredients of 
plant food. It ought to be plainly evident, however, if a 
soil is but sparingly provided with available potash and 
phosphoric acid, that liberal applications of nitrates will 
cause these other soil ingredients to become exhausted 
much sooner than otherwise. In such cases the nitrates 
have not acted as stimulants, but have merely furnished 
the missing ingredient required in the manufacture by 
the plant of the readily available potash and phosphoric 
acid of the soil, into the finished crop product. It must 
be obvious that these materials cannot be utilized in the 
building of plants and still remain in the soil for the benefit 
of crops which follow. 



NITRATE OF SODA 145 

264. Nitrate of soda yields quick returns on the manurial 
investment. — The old idea that the more the effect of a 
fertilizer can be prolonged in the soil, the more economical 
it is, must give way to the idea that the quicker the returns 
on the money invested in the fertilizers, the greater are 
likely to be the net profits. It is, however, important to 
recognize that there may sometimes be cases in which a 
given investment in a large quantity of a very cheap, slowly 
acting fertilizer may be more remunerative than the pur- 
chase for the same sum of money of a small amount of 
one which acts quickly. In such cases the price per ton, 
the amount of plant food contained therein, the danger of 
loss or of unfavorable transformations resulting in the soil, 
and the length of time before it will be possible for the 
plants to make use of it, must all be given due considera- 
tion. When so considered, nitrate of soda will not be looked 
upon as a " stimulant " or as something to be avoided, but 
as an excellent fertilizer. Nevertheless, nitrate of soda is 
a fertilizer which must be used with good judgment. 
One must consider not only the length of the period of 
growth of the plants concerned, but also their special 
characteristics and requirements. Attention must also 
be paid to the character of the soil as concerns the possi- 
bilities of loss by drainage ; and to the effect of the nitrate 
of soda upon the soil texture and its chemical reaction. 

265. Possible effects of nitrate of soda on the micro- 
organisms of the soil. — To what has preceded may be 
added the possible consideration of the effect of the nitrates 
upon the microscopic plant and animal life of the soil, 
since a disturbance of the numerical relation of certain of 
these two forms and even of the different microscopic 
plants (including bacteria) may have a marked influence 
upon the productivity of the soil. 



146 FERTILIZERS 

266. Ammonium nitrate. — At present ammonium ni- 
trate (NH4NO3) is rarely used for agricultural purposes 
because of its high cost ; yet it is a most excellent ferti- 
lizer, especially where it is desirable to employ a source of 
nitrogen which will leave in the soil no objectionable 
residues. Such conditions are most frequently met with 
in greenhouses, where, owing to the great value of the 
product from a small area, its use may often be permissible. 
Ammonium nitrate contains 35 per cent of nitrogen, one 
part existing in ammoniacal and the other in nitrate form. 
This material possesses one very distinct advantage over 
all of the usual nitrogenous fertilizers, for the reason that 
the cost of transporting a unit of nitrogen is very low. 
This is on account of its concentrated character and the 
fact that it does not contain some occasionally useless or 
low-priced ingredient such as soda or lime. 

267. The synthetic production of ammonia and am- 
monium salts. — Experiments are now being conducted 
which have shown the possibility of the synthetic produc- 
tion of ammonia by the compression of hydrogen and 
nitrogen at high temperatures in the presence of uranium 
oxid, pure iron, and of other catalyzers. If this process 
can be placed on an economic basis, as is claimed, the 
manufacture of ammonia and of nitric acid may yet be 
made so cheap that ammonium nitrate can be generally 
used as a fertilizer. An important feature of this process 
is that the union of the gases does not depend upon power- 
ful electric currents. On this account great water 
power is not vital to success, and the manufacture can 
therefore be carried on practically anywhere. 



CHAPTER XIV 

AMMONIUM SALTS AND CALCIUM CYANAMID 

The ammonium salt of the greater agricultural impor- 
tance at present is ammonium sulfate. This is derived 
chiefly from the destructive distillation of coal in coke 
ovens, blast furnaces, gas works, and elsewhere. 1 

268. The manufacture of ammonium sulfate. — It is 
asserted that the first attempt to recover the ammonia in 
connection with the manufacture of coke was made by 
Stauf in 1764, but the first satisfactory plant for this pur- 
pose was not erected until 1858, when one was established 
at St. Denis. 

The amount of nitrogen in coal ranges from 1.5 to 2 
per cent, and of this only about 15 per cent is transformed 
into ammonia and recovered in the water used for washing 
the gas. The ammonia is redistilled from this water, 
collected in sulfuric acid, and the resulting sulfate of 
ammonia is won by crystallization. It yields a white, 
yellowish, or gray salt containing about 20.5 per cent of 
nitrogen. The appearance of the yellow, gray, or occa- 
sional blue or brown color may be due to traces of tarry 
products, ferrocyanid, formed from cyanids which are 
usually present, and to materials sometimes accompany- 
ing thiocyanates. 

269. Thiocyanates a former toxic impurity of ammo- 
nium sulfate. — The presence of thiocyanates is readily 

1 For the details of this process, see The Manufacture of Chemical 
Manures, by Fritsch, London, 1911. 

147 



148 FERTILIZERS 

recognized by the reddish coloration produced when ferric 
chlorid is added to a watery solution of sulfate of am- 
monia. Its occurrence in quantities sufficient to be deadly 
to vegetation has been noted in sulfate of ammonia sold 
in Europe ; but because it is so easily recognized, and the 
importance of its avoidance is now so well understood, 
it is seldom encountered. It was present a few years 
ago in a lot of sulfate of ammonia sold in Rhode Island, 
but the quantity was found by experiment insufficient to 
prove positively toxic to the usual farm crops. 

270. Chemical composition of sulfate of ammonia. — 
When pure, sulfate of ammonia contains 21.2 per cent of 
nitrogen. The commercial product is usually sold under 
a guaranty of 20.2 per cent of nitrogen or 24.5 per cent of 
ammonia. 

271. Sulfate of ammonia must not be mixed with 
alkaline substances. — Owing to the ease with which 
ammonia is liberated by alkalies, sulfate of ammonia 
should never be mixed, before its application, with wood- 
ashes, potassium carbonate, slaked or burned lime, basic 
slag meal, or other materials of similar basic character. 
Considerable losses have been said to result after the 
application of sulfate of ammonia to a rich garden soil 
that had been liberally limed. Similar losses also occur 
from light calcareous soils in times of drought. Ordi- 
narily, however, there is but little loss of ammonia by 
volatilization when sulfate of ammonia is applied to soils 
as a fertilizer, under the usual conditions and in the usual 
amounts. Indeed, there is much evidence to this effect, 
even in the case of soils which have been adequately, 
though not excessively, limed. 

272. Absorption of sulfate of ammonia by soils. — 
The ammonia of ammonium salts is usually readily ab- 



AMMONIUM SALTS AND CALCIUM CYANAMID 149 

sorbed by soils, in such a way that it is less subject than 
nitrates to immediate losses by leaching. This is prob- 
ably due to the fact that the ammonia enters at once 
into chemical combinations with certain organic salts, 
formed by the reactions of lime and magnesia with prod- 
ucts of decaying vegetable matter, and also with zeolites 
and possibly other similar compounds of the soil. The 
sulfuric acid of the sulfate of ammonia unites with the 
bases which are replaced by ammonia. The ammonia, 
in these combinations which result in the soil, nevertheless 
yields readily to nitrification. 

273. The use of sulfate of ammonia exhausts soils of 
lime. — It was long supposed that most of the ammonia 
thus retained by soils was transformed at once and held 
as ammonium carbonate, the compound which results 
from the reaction of ammonium sulfate with calcium 
carbonate, as follows : — 

(NH 4 ) 2 S0 4 + CaC0 3 = (NH 4 ) 2 C0 3 + CaS0 4 • Aq. 

ammonium calcium ammonium calcium 

sulfate carbonate carbonate sulfate 

By this reaction calcium sulfate (land plaster or gypsum) 
is formed, which in time is largely lost by its solution and 
passage into the drainage waters, whereby the soils grad- 
ually become deficient in lime. Furthermore, by the 
later nitrification of that portion of the ammonia which 
is not changed to carbonate at the outset, the nitric 
acid which is formed unites with further quantities of 
lime and magnesia, whereby the soil becomes still more 
depleted of its available carbonates, and hence tends to 
develop acidic conditions. 

274. Nitrogen of sulfate of ammonia fixed by micro- 
organisms. — Nitrogen in ammonia, like that in nitrate 



150 FERTILIZERS 

of soda, is subject to more or less fixation by its being 
taken up by, and becoming a part of the organized struc- 
ture of, the bacteria, fungi, and other minute plant and 
animal denizens of the soil. 

275. The efficiency of sulfate of ammonia as a fertilizer. 
— It was concluded by Wagner and Dorsch and has been 
well substantiated by other experimenters that, as a 
general rule, nitrogen in sulfate of ammonia possesses 
about nine-tenths the efficiency of nitrogen in nitrate of 
soda. The difference of one-tenth may be attributed in 
part to possible small losses of ammonia by volatilization, 
but chiefly to the transformation of some of the nitrogen 
into organic forms, such, for example, as the structure of 
the organisms which effect its transformation into nitrates. 
Such a generalization as to the relative efficiency of sul- 
fate of ammonia is nevertheless capable of only restricted 
application, for with other plants than the cereals, which 
have been commonly used in such experiments, somewhat 
different conclusions might be drawn. This is especially 
true if no account is taken of the possible physiological 
functions of the soda, especially where the potash supply 
is deficient. This is plainly shown by a study of a tabu- 
lation by Stutzer 1 of a large number of European ex- 
periments with nitrate of soda and sulfate of ammonia 
in which, as far as concerned the cereals, nitrate of soda 
sometimes gave even poorer results than the sulfate of 
ammonia. With mangel wurzels and sugar beets, how- 
ever, the results were almost invariably much in favor of 
the nitrate of soda. This, as explained elsewhere, may 
have been due to a correction of the chemical reaction of 
the soil by the soda of the nitrate of soda, to a conserva- 
tion of the available potash supply by virtue of soda being 

1 Der Chilisalpeter, Berlin. 



AMMONIUM SALTS AND CALCIUM CYAN AMID 151 

taken up in its stead, by the soda having been of benefit 
to the plants physiologically, or in still other ways. 

276. Soda important in trials of nitrate of soda and 
sulfate of ammonia. — All of the points which have been 
mentioned emphasize the importance of taking soda into 
account in comparing the efficiency of the nitrogen in 
these compounds. A precaution which may be taken is 
to add to the pots or plots of land which receive the sulfate 
of ammonia as much sodium carbonate as would be formed 
from the nitrate of soda. If this precaution is not taken, 
it becomes doubly imperative to determine by check tests 
if enough potash is actually present to fully meet the alkali 
requirements of the plants under experiment. The need 
of considering the possible effect upon the soil reaction 
which may be exerted by the residual sodium carbonate 
derived from the nitrate of soda will obviously be deter- 
mined very largely by the character of the soil at the outset, 
and by the adaptations of the plants employed in the ex- 
periments. 

277. Double decompositions follow the use of ammo- 
nium salts. — In the course of the Rothamsted experi- 
ments it was found that when ammonium chlorid and 
ammonium sulfate were applied to the land, chlorin and 
sulfuric acid began to appear almost at once in the 
drainage waters, combined with the lime and magnesia 
which the ammonia had replaced in the soil. As has been 
explained in another connection, the nitric acid formed in 
soils as a result of the nitrification of the ammonia may 
combine with lime, magnesia, or even with potash and 
soda. 

On account of the acid, in combination, in the sulfate 
of ammonia at the outset, the drain on the lime and mag- 
nesia of the soil arising from the use of sulfate of ammonia. 



152 FERTILIZERS 

is far greater than that created by the employment of 
dried blood and other sources of organic nitrogen, which, 
when nitrified, leave but one acid to be neutralized by the 
soil bases. Incidentally this tendency to the develop- 
ment of soil acidity by the use of organic nitrogenous 
materials, just as is eventually the case by the use of sul- 
fate of ammonia, does not appear to have been sufficiently 
appreciated, and it is usually entirely overlooked. 

278. Partial soil sterility sometimes caused by sulfate 
of ammonia. — Many cases of marked inferiority of sul- 
fate of ammonia as a source of nitrogen had long been on 
record, but the reason for the very inferior results had not 
been carefully studied until it was taken up apparently 
coincidently by Wagner and Dorsch in Germany and at 
the Rhode Island experiment station. In the year 1890 
it was observed at the latter station that sulfate of am- 
monia was highly toxic, even the first season of its applica- 
tion. At other points in the state of Rhode Island it 
either became quickly toxic or gave evidence of a tendency 
in that direction. The experiments of the succeeding 
three years proved conclusively that this toxic action was 
due to the creation of an acidic condition of the soil which, 
either directly or by virtue of toxic substances to which 
it gave rise, was highly destructive to many varieties of 
agricultural plants. It was also shown that this condition 
could be corrected by sodium carbonate, potassium car- 
bonate, caustic magnesia, carbonate of lime, slaked lime, 
calcium oxalate, and calcium acetate, but that when these 
bases were combined with chlorin or sulfuric acid, they 
were usually of no practical value as correctives of the 
condition. Toward the close of the same decade the 
experiments by Voelcker at Woburn, England, in which 
an occasional inferiority of action of the ammonium salts 



AMMONIUM SALTS AND CALCIUM CYANAMID 153 

had already been observed, gave evidence of a highly 
toxic effect upon barley. This was shown later to have 
been due apparently to the development of soil acidity, 
and to be capable of correction by liming. 

279. The conditions caused in acid soils by sulfate of 
ammonia not fatal to all plants. — In the course of the 
earlier experiments with sulfate of ammonia, at the Rhode 
Island experiment station, it was found that conditions 
were produced thereby which were prohibitive of the 




Fig. 11. — Limed Grasses. 
Timothy at left, redtop at right. Sulfate of 
ammonia. Compare with Fig. 12. 

successful growth of lettuce, spinach, beets, Swiss chard, 
cress, kohl-rabi, cabbage, cauliflower, asparagus, canta- 
loupes, clover, alfalfa, string beans, peas, vetch, Kentucky 
blue-grass, timothy, and many other plants. Neverthe- 
less, these conditions failed to interfere with the successful 
growth of the blackberry, Norway spruce, watermelon, 
common sorrel, cranberry, and other plants. In fact, sev- 
eral of these latter plants seemed to thrive best of all 
under conditions which were exceedingly toxic to plants 
of other kinds. In 1909, after having made sixteen sue- 



154 



FERTILIZERS 



cessive annual applications of sulfate of ammonia, and 
after the soil had become still more toxic to most plants, 
than in the earlier years, it was found that the conditions 
for the growth of the flowering perennial, Silene orientalis, 
were better than where lime had been used and where, 
by its application, the conditions formerly toxic to most 
plants had again been made highly favorable. This 
emphasizes the fact that any discussion of toxic substances 

in the soil must 
embrace a consid- 
eration of the par- 
ticular variety of 
plant involved. 

The observa- 
tions at Woburn 
with a mixture of 
ammonium chlo- 
rid and of am- 
monium sulfate 
agree with those 
made in Rhode 
Island, with am- 
monium sulfate, 
in showing that 
barley is more sensitive than wheat to the toxic condi- 
tions produced. This difference has been attributed by 
Hall to the deeper rooting habit of the wheat than of 
the barley, and to a more robust constitution of the 
wheat plant. Many of the observations made in Rhode 
Island, in the course of which several hundred different 
varieties of plants have been tested, fail to support the 
idea that the different depth of the roots of plants is the 
chief, or, in some cases, even an important, determining 




Fig. 12. — Unlimed Grasses. 
Timothy at left, redtop at right. Sulfate of 
ammonia. Compare with Fig. 1 1 and note how 
soil acidity has lessened the proportion of tim- 
othy. 



AMMONIUM SALTS AND CALCIUM CYANAMID 155 

factor. The results indicate that the explanation of these 
differences in plants must often be sought in quite other 
directions. In fact, in the course of the Rhode Island 
experiments the mangel wurzel, which Hall, in comparison 
with barley, calls a " deep rooting " plant, was subject to 
injury in a far greater degree than barley, when sulfate of 




Fig. 13. — Effect of Treatment on Common Sorrel. 
Dried blood, sulfate of ammonia, and nitrate of soda, respectively, 
from left to right. Fertilized alike with potash and phosphoric acid. 
The more acid the soil was made, the better the growth. Nitrate of 
soda lessens acidity. 



ammonia was used without lime. This difference in the 
two kinds of plants was not only true of soils where sulfate 
of ammonia had been applied previously, but also of those 
poor in lime in many different parts of Rhode Island, and 
even when nitrate of soda was the only artificial source of 
nitrogen employed. 

280. Sulfate of ammonia an aid in rendering certain 
grasses dominant. — In connection with the permanent 



156 • FERTILIZERS 

grass experiments at Rothamsted, it was found that the 
use of ammonium salts (ammonium chlorid and ammo- 
nium sulfate) made the presence of sweet vernal grass 
(Anthoxanihum odoratum L.) and sheep's fescue (Festuca 
ovina L.) prominent, — a fact attributed to the holding of 
the ammonia in the surface soil and to the shallow rooting 
habit of these grasses. It has been found, however, at 
the Rhode Island experiment station that an acidic ferti- 
lizer, of which sulfate of ammonia was one constitutent, 
when used successively upon certain grass plats, has driven 
out Kentucky blue-grass, clover, and certain other grasses 
and weeds, leaving red fescue (Festuca rubra L.) and 
sheep's fescue in practically undisputed possession of the 
land. Where, on the contrary, basic fertilizers have been 
used, in which the sulfate of ammonia is replaced by nitrate 
of soda, and acid phosphate by basic slag meal, Kentucky 
blue-grass, white clover, and other grasses and weeds have 
almost obscured the fescues. It is also true that these 
fescues have become dominant on old meadows where 
natural acidic soil conditions, due to lack of carbonate of 
lime, inhibit the growth of many other species of grass. 
It may therefore be questioned whether the shallow root- 
ing is the sole or even dominant factor in the survival of 
these grasses, and if the chemical reaction of the soil, 
special ability to utilize ammonia or even unnitrified nitrog- 
enous substances, and resistance to soil compounds which 
are toxic to other plants, may not be equally important 
factors. 

281. Sulfate of ammonia may cause the suspension of 
certain bacterial activity. — Sulfate of ammonia, if used 
to the extent of creating highly acidic conditions in the 
soil, causes the suspension, at least to a great extent, of the 
normal bacterial life and gives rise to the growth of molds, 



AMMONIUM SALTS AND CALCIUM CYANAMID 157 

fungi, and doubtless to special types of bacteria suited 
to the unusual conditions. It was found, for example, 
in connection with the permanent grass experiments at 
Rothamsted, that where sulfate of ammonia had long been 
used, nitrification had practically ceased ; and the grass 
plants were therefore supposedly forced to utilize ammonia 
or combined nitrogen, instead of nitrates. 

The Rothamsted experiments show that barley ripens, 
and mangel wurzels cease their growth, earlier, when 
manured with ammonium salts than when grown with 
the aid of nitrate of soda. This has been explained at 
Rothamsted as due to the greater descent of the nitrates 
into the soil and hence to a deeper rooting habit of the 
plants, induced thereby, especially in dry seasons, on 
which account the plants are better supplied with water. 
The Rothamsted experiments show, nevertheless, that 
in such dry seasons sulfate of ammonia acts relatively 
better than in wet ones, due supposedly to higher soil 
temperatures, to better aeration, and hence to a better 
chance for nitrification. On this account, in moderately 
dry seasons, the ammonia would be expected to nitrify 
rapidly, and when so nitrified it is as movable in the soil 
as the original nitrate ; hence the preceding explanation 
would not seem to be adequate in all cases. In fact, it 
seems probable, in view of the possible lack of potash and 
of the now well-established plant food value of soda under 
such circumstances, especially for mangel wurzels, that 
the soda itself may have been a factor in keeping up the 
longer growth and also in causing the usually greater crop. 

Experiments by Maercker, and by Wagner and Dorsch, 
show that barley is relatively more responsive than the 
other cereals to nitrate of soda. Wagner also observed 
that barley is dependent, to a far greater degree than oats, 



158 FERTILIZERS 

upon potash manuring. On account of this fact, he ex- 
plains that the better action of nitrate of soda than of 
sulfate of ammonia, upon barley, is due to the fact that 
the soda comes more into play by way of performing a part 
of the functions of potash. 

282. Sulfate of ammonia liberates plant food. — Ac- 
cording to the accepted idea that the ammonia of sulfate 
of ammonia can replace lime, magnesia, potash, and soda, 
when the latter are held in zeolitic combinations in the 
soil, it is evident that the use of sulfate of ammonia is 
likely to result in the liberation of these plant food ingre- 
dients ; and if employed in excess without other fertilizers, 
it may finally result in seriously impoverishing the soil. 
This fact is fully substantiated by the studies of drainage 
waters made by Voelcker and by Lawes and Gilbert. 
The compounds which were chiefly increased in the drain- 
age waters, upon the application of ammonium salts, 
were chlorids, sulfates, and calcium nitrate. It was 
found that 400 pounds of sulfate of ammonia removed 
from the soil annually in this way about 172 pounds 
of lime. 

283. Ammonium salts fleeting in their effects. — Not- 
withstanding that ammonia enters readily into zeolitic 
and other chemical combinations in the soil, it is not ca- 
pable of being continuously held for successive years. 
This is shown by experiments at Rothamsted in which 
mineral fertilizers were alternated through a long series 
of years with ammonium salts ; for in the alternate years 
when only mineral fertilizers were applied, the yield aver- 
aged about the same as where the same mineral fertilizers 
were used continuously without any ammonium salts. 
These results further support the fact of the rapid trans- 
formation of the ammonia into nitrates in the soil. They 



AMMONIUM SALTS AND CALCIUM CYAN AMID 159 

also show that the same care must be exercised in the em- 
ployment of the ammonium salts as in the application of 
nitrates, in order that no more may be applied than will 
be utilized in the same season. 

It was found by Voelcker, Frankland, and others that 
the larger the application of ammonium salts in the spring, 
the greater were the losses of nitrates in the drainage water 
the following December. The loss which resulted in this 
way was found to amount to 8.5 pounds of nitrogen per 
acre for each inch of rainfall lost by leaching. After an 
autumn application of ammonium salts at the rate of 600 
pounds per acre, Frankland found the loss of nitrogen 
equal to 18 pounds per acre for each inch of rainfall lost 
by percolation. 

284. Ammonium salts leach less quickly than nitrates. 
— Even if the employment of considerable amounts of 
ammonium salts in the autumn has been found to be un- 
economical, it is nevertheless true that in making spring 
applications the danger of immediate losses by leaching 
are less, in the case of ammonium salts, than in connec- 
tion with nitrates. 

285. Ammonium sulfate may cause injury on light 
calcareous soils. — It was observed by Deherain at 
Grignon, France, that on light calcareous soils an efflor- 
escence of calcium sulfate followed applications of ammo- 
nium sulfate, after a few days of drought. The physical 
condition of the soil was so seriously injured in conse- 
quence, that the ill effects of drought were much height- 
ened, and, furthermore, the injury lasted for several sea- 
sons. On soil of the same character, nitrate of soda was 
nevertheless highly beneficial. 

For several reasons Deherain has recommended the 
restriction of applications of ammonium salts to stiff or 



160 FERTILIZERS 

heavy land, and even then to quantities ranging from 140 
to 175 pounds per acre. 

286. Ammonia may injure plants. — It appears to be 
well established that sufficient ammonia may enter the 
plant to exert a granulating or coagulating effect upon 
the protoplasm, a result which is inimical to plant life. 
Nevertheless, Hosaus, Adolf Mayer, and others have found 
small amounts of ammonia present in normal plants, and 
Mayer has demonstrated that plants can utilize nitrogen 
in ammonia, though probably not as safely and success- 
fully in most instances as when it is taken up from nitrates. 
There are, nevertheless, certain classes of plants that prob- 
ably take up their nitrogen chiefly or almost wholly in 
ammonia and in still higher soluble nitrogenous compounds, 
for they thrive splendidly in locations where nitrification 
is practically suspended. The foregoing applies even to 
plants which are not supposed to derive their nitrogen 
through the aid of symbiotic bacteria or through the pos- 
sible intervention of mychorhiza. 

A reason advanced for the usual better action of nitrates 
than of ammonium salts is that even if the former are 
reduced to ammonia in the soil, the change takes place 
so gradually that the resultant ammonia does not accu- 
mulate in sufficient amounts to cause injury. The am- 
monia in such cases is built up through successive stages 
into the final nitrogenous compounds of the plants, prac- 
tically as rapidly as it is formed. 

Experiments by Lehmann and others show that in 
some cases nitrates are apparently preferable in the 
early stages of the growth of certain plants, whereas, 
later, ammonia gives better results ; nevertheless, in 
the case of still other kinds of plants these conditions 
were exactly reversed. 



AMMONIUM SALTS AND CALCIUM CYANAMID 161 

287. Calcium cyanamid a new product. — A nitroge- 
nous fertilizer which has been rendered possible by the 
recent electrical development is calcium cyanamid, known 
commercially as " nitrolime " " nitrolim " and " lime- 
nitrogen," and in Germany as "Kalk-stickstoff." 

288. The manufacture of calcium cyanamid. — The 
process for the manufacture of calcium cyanamid, which 
was placed on a commercial basis by Frank and Caro of 
Berlin, Germany, is based upon the employment of cal- 
cium carbid, which combines readily with nitrogen gas at 
moderate temperatures, yielding the calcium cyanamid 

(CaC 2 + N 2 = CaCN 2 + C). 

calcium nitrogen calcium carbon 
carbid cyanamid 

The calcium cyanamid in turn may be completely decom- 
posed by steam at high pressure, yielding ammonia and 
calcium carbonate 

(CaCN 2 + 3 H 2 = 2 NH 3 + CaCo 3 ). 

calcium water as ammonia calcium 
cyanamid high pres- carbonate 

sure steam 

Thus it may be used in the manufacture of ammonium 
salts. 

In the practical carrying out of the process, the calcium 
carbid is ground coarsely and is then placed in iron tubes 
through which, while subjected to heat, a current of nitro- 
gen gas is passed. 

It is possible to produce the carbid and cyanamid simul- 
taneously, but in actual practice it has been found prefer- 
able to separate the processes. 

The preparation of the nitrogen gas which is required, 
may be accomplished by passing air over red-hot copper. 
The oxygen combines with the copper to produce copper 



162 FERTILIZERS 

oxid, thus leaving the nitrogen gas behind. The copper 
oxid is then reduced by passing over it, while hot, a cur- 
rent of coal gas. 

Nitrogen gas is more commonly obtained for the pur- 
pose of the manufacture of calcium cyanamid by the frac- 
tional distillation of liquid air. In this process the oxygen 
is separated from the nitrogen, the former being then 
utilized for various other purposes. 

The first works for the extensive manufacture of calcium 
cyanamid were established by an Italian company, the 
Societa Generale per la Cianamide, of Rome, which in 
turn embraces two companies organized for distinct 
purposes. Works have already been established in 
several different countries, including two in the United 
States. 

It is claimed that one electrical horse power is capable 
of fixing 772 kilograms of nitrogen per annum, but the 
yield actually secured in practice is only from 300 to 330 
kilograms. 

289. Changes in calcium cyanamid resulting in the 
soil. — The calcium cyanamid is a light, fine, dark gray 
powder. Owing to its high content of calcium oxid, it 
readily takes on water until the lime is slaked. At the 
same time the calcium cyanamid itself slowly decomposes, 
according to the reaction indicated above, with gradual 
liberation of ammonia. 

The views as to the changes taking place in cyanamid 
in the soil have undergone more or less modification. It is 
now asserted that the first change which takes place is the 
formation of urea 

(CaCN 2 + H 2 = Ca(OH) 2 + CO(NH 2 ) 2 ), 

calcium water calcium urea 

cyanamid hydrate 



AMMONIUM SALTS AND CALCIUM CYAN AMID 163 

and that the urea then breaks up through bacterial 
agencies, forming ammonium carbonate, which by 
nitrification is transformed into nitric acid. The nitric 
acid reacting finally with the calcium carbonate results 
in the production of calcium nitrate, though of course the 
formation of other nitrates is also possible. 

290. The utilization of calcium cyanamid for the manu- 
facture of urea and other substances. — It has also been 
found that calcium cyanamid may be utilized in the prac- 
tical manufacture of urea ; it has likewise been employed 
in the production of guanidin ; and even of creatin, one of 
the substances present in human muscle and found in meat 
extract. 

291. Calcium cyanamid as a fertilizer. — As a fertilizer, 
calcium cyanamid compares well in efficiency on heavy 
soils with sulfate of ammonia, but it has been found to be 
more or less toxic to young plants, due supposedly to the 
formation at the outset, through the action of water, of 
some dicyanamid. Such injury is said to be avoided if 
it is introduced into the soil long enough in advance of the 
time of seeding or planting. Calcium cyanamid has the 
advantage over sulfate of ammonia for acid soils, of having 
an ultimate basic, rather than acidic, effect. 

292. Practical difficulties connected with calcium cyan- 
amid. — In order to remove some of the difficulties con- 
nected with the losses of ammonia, to facilitate handling, 
and for other reasons, it has been proposed to mix with the 
calcium cyanamid a small quantity of peat, but there are 
objections to such a plan, in view of the additional cost of 
transportation. The product as manufactured and sold 
in the United States, for a time, was said to be subjected 
to an additional treatment, the object of which was to 
increase its stability and thus obviate the possible loss 



164 FERTILIZERS 

of ammonia. In one of the processes the lime was fully 
slaked, and nitrate of soda was said to be introduced during 
the process to keep down the temperature. It has also 
been proposed to treat the material with sulfuric acid to 
a limit which would prevent the tendency to decompose 
with loss of ammonia. Finally, it has been stated that the 
plan of minimum hydrating has superseded the latter 
process. In any event, the calcium cyanamid industry 
is at present probably only in its infancy, and the recent 
difficulties connected with its more general utilization in 
the great fertilizer manufacturing industry will doubtless 
be more fully overcome in the near future. 

293. The output of calcium cyanamid. — The produc- 
tion of cyanamid in the United States had reached in 1912 
a limit of 12,000 tons per year at the factory in Niagara 
Falls, and other works are likely soon to add greatly to 
the output. 

The total sales of cyanamid are claimed to have risen in 
two years to 4,000,000 tons per annum. 



CHAPTER XV 

NATURAL PHOSPHATIC FERTILIZERS 

Phosphorus is said to have been discovered in 1669 
by the alchemist Brandt, a merchant of Hamburg, while 
searching in urine for the philosopher's stone. It was also 
discovered independently by the chemist Kunkel, of 
Berlin, and in 1688 it was extracted by Albinus from the 
seeds of the mustard and cress. 

The discovery of phosphoric acid was made by Margraff 
in 1743, who by calcining it with charcoal reconverted it 
into phosporus. 

It was not until 1769 that Gohn, a Swedish chemist, 
found phosphoric acid in bones; and a little later the 
Swedish chemist Scheele developed a practical process of 
recovering the phosphorus from them. 

It was not until more than a century after phosphorus 
was discovered that its mineral nature was ascertained by 
Gohn, who found it in pyromorphite, a lead phosphate. 
Soon thereafter the discovery of the presence of phosphorus 
in the mineral apatite was made by Vauquelin and Klaproth. 

294. Bone as a fertilizer. — The use of bone as a fer- 
tilizer is such an ancient practice that it is now impossible 
to establish definitely when or where it had its origin. Its 
employment is mentioned by many English writers from 
1653 to the beginning of the last century, and in England 
the value of bone as a fertilizer came to be generally rec- 
ognized much earlier than anywhere on the continent of 
Europe. In fact, it is recorded that machines for grinding 

165 



166 FERTILIZERS 

bone were already in use in England by 1778, though they 
were obviously crude and not calculated to reduce the 
material to the same degree of fineness, as modern mills. 

As early as 1815 the English supply of bones had become 
so inadequate that they were imported from the continent 
of Europe in ever increasing quantities, the importations 
soon reaching 30,000 tons per annum. It has been stated 
by Liebig that even the battle-fields of Leipzig, Waterloo, 
and the Crimea were turned up by the English in their 
search for bones. 

According to Heiden, the value of bone as a fertilizer 
was not generally recognized in Germany until from 1855 
to 1885. 

With the discovery of other phosphates the importa- 
tions of bone into England became less, but they have 
again increased ; for as late as 1907 it was reported that 
46,115 tons were brought into England in a single year. 
Of this quantity 32,800 tons came from Argentina and 
India, and the rest from other countries. 

295. The chemical composition of bone. — The com- 
position of bone varies in different parts of the same ani- 
mal, according to its age, health, and sometimes also with 
the character of food which it has consumed. There is 
also a variation in the composition of bones, similarly 
located, in the different kinds of animals. Bone is com- 
posed of both mineral and organic matter. The former is 
assumed to consist chiefly of tricalcium phosphate 

O O 

(Ca 3 (P0 4 ) 2 or Ca<^P-0-Ca-0-P^>Ca), 

though it also contains very small quantities of magnesia 
and fiuorin. In the case of bones which are not care- 



NATURAL PIIOSPIIATIC FERTILIZERS 167 

fully prepared, traces of fluorin, sodium, and iron are fre- 
quently found which are present in slight residues of 
blood. 

The organic matter of the bone includes ossein, col- 
lagen, and chondro-mucoid. The ossein when dry contains 
about 17 per cent of nitrogen and may be converted by 
long heating with water into glue and gelatine. The 
following statement by Murray shows quite fully the 
constituents and average percentage composition of the 
fresh bones of mammals : — 

Per Cent 



Organic matter 


67 
• M ossein 




6.7 
14.6 
25.4 = 


= 4.0 nitrogen 


Ash .... 


[P2O5 
. 53.3 CaO 

[ Mg. F, 


etc. 


22.3 = 
29.2 
1.8 


= 48.7 Ca 3 (P0 4 ) 2 



100.0 100.0 

296. Composition of the ash. — When bones are burned, 
only the mineral matter remains behind, and this is known 
as bone ash. If bones, on the other hand, are treated for 
a long time with dilute hydrochloric acid, the mineral 
matter is dissolved and the organic framework of the bone 
remains, still possessing its original form. 

297. Composition of weathered bones. — In the case 
of bones which have been burned for a time, or which have 
lain exposed to the weather, considerable of the organic 
matter has been lost, and they are therefore poor in nitro- 
gen, but richer in phosphate than fresh bone. 

298. Treatment of bone for the removal of fat. — The 
treatment of bones for the removal of fat may consist in 
boiling, steaming at high pressure, or extraction with 
naphtha or other solvents. The fat is in such demand 
and has such a high commercial value that it is now 



168 FERTILIZERS 

usually removed from bones, more or less completely, be- 
fore they are marketed for fertilizer purposes. The bones 
are ground and sold as fine or coarse ground bone, accord- 
ing to the degree of fineness. Such bone usually contains 
from 1.5 to 4 per cent of nitrogen. 

After the extraction of the fat by means of a solvent, or 
by boiling in water, bones are sometimes subjected to high 
steam pressure for the removal of gelatine. In some cases, 
also, the bone is treated directly with steam at high pres- 
sure, which removes most of the fat and much of the ossein 
in a single operation. After bones have been steamed in 
this manner, they crumble readily and can be ground with 
ease to a fine powder. The material is sold in this country 
under the name of " fine-ground steamed bone," although 
the designation " steamed " is often omitted. 

299. Effect of steaming on the nitrogen content. — 
Bone, if subjected to severe steaming, may not contain 
more than from 1 to 1.5 per cent of nitrogen instead of 
from 2 to 4 per cent, as would otherwise be the case. 
On account of the removal of so much of the organic 
matter in such cases, the content of phosphoric acid 
may rise to from 27 to 30 per cent, which is from 5 to 6 
per cent above the amount usually found in commercial 
bone. 

300. Bone wastes from industries. — Bone is used for 
the manufacture of buttons, knife handles, and a vast 
number of other articles; the wastes from which are 
ground and sold as bone meal or are used in compound- 
ing commercial fertilizers. 

When bone is subjected to destructive distillation, animal 
charcoal, containing about 10 per cent of carbon, is pro- 
duced, in a manner analogous to the production of wood 
charcoal from wood. This material is employed in sugar 



NATURAL PIIOSPHATKJ FERTILIZERS 169 

refineries for clarifying sugar solutions, and when no longer 
fit for such use it is either reduced to bone ash, or it is 
treated with sulfuric acid. By the latter process the bone- 
black is transformed into a superphosphate known com- 
mercially as " vitriolated " or " dissolved " bone-black. 
Bone is sometimes used in the process of annealing, as a 
result of which it loses much of its nitrogen and becomes 
highly carbonized, consequently closely resembling bone- 
black. Such material, though occasionally sold for use 
directly as a fertilizer, should preferably be treated with 
sulfuric acid before its application to the soil. 

301. Fermentation and other methods of disintegrating 
bone. — In England and elsewhere bones are sometimes 
moistened with water and allowed to ferment in heaps, 
which process renders them more available. 

Bones have also been treated in tanks with urine from 
cow stables which causes them to gradually soften and 
disintegrate. 

The process of steaming increases greatly the solubility 
of bone in ammonium citrate, and it is usually conceded to 
greatly increase the availability of the phosphoric acid to 
plants, though it has been found by Kellner, in Japan, in a 
moist and hot climate, that bone before steaming was even 
more available than afterwards. 

302. Bone meal as a fertilizer. — ■ The most ideal soils 
on which to use " undissolved " bone meal, whether 
steamed or raw, are those which are open and inclined 
to be sandy or gravelly, though they should not be too 
dry. On the other hand, bone acts more slowly on heavy 
clay and silt soils. 

For many years bone meal was the favorite fertilizer 
of the American farmer, not only on account of its well- 
known power to immediately increase crops to a consider- 



170 FERTILIZERS 

able extent, but chiefly because of its accredited lasting 
qualities. (See Fig. 14.) 

In recent years the use of acid phosphate and of other 
superphosphates has increased to such an extent as to keep 
bone down to a price which still admits of its frequent 
agricultural use. At the same time, on account of the 
greater demand for vegetables and for early garden 
crops, which must reach a marketable stage in the shortest 
possible time, many farmers have come to a realization of 
the fact that it is often better oconomy to expend money 
for quick-acting acid phosphate rather than to tie up in the 
soil, for some years, a large investment in bone. 

Bone meal is a favorite substance for application before 
seeding land to clover and grass. It is also much used for 
fruits, hops, and for crops which require a long season in 
which to mature. 

If bone meal is applied continually for many years to a 
soil in need of liming, it very gradually tends to correct 
the condition ; but not rapidly enough to justify waiting 
for it to do this work. In fact, basic slag meal is far more 
efficient in this direction than bone meal, and it is at the 
same time a more quickly available phosphate. 

For plants and soils which need liming, it is always 
more economical to lime the land at the outset, no 
matter what the form of phosphate to be used, than to 
wait for the phosphate to gradually correct the exist- 
ing conditions. 

303. The soluble and reverted phosphoric acid of bone. 
— Ground raw bone and steamed bone rarely yield much 
more than 0.5 per cent of " soluble " phosphoric acid 
upon long and thorough leaching with distilled water, 
and raw bone is but slightly soluble in neutral ammo- 
nium citrate solution, at the usual temperature of 65° C. 



NATURAL PIIOSPHATIC FERTILIZERS 171 




172 FERTILIZERS 

at which " reverted " phosphoric acid is determined. 
Steamed bone, on the contrary, yields a considerable per- 
centage of reverted phosphoric acid, which, added to the 
soluble, makes up the " available " phosphoric acid re- 
ported by analysts. It is probable that the reverted or 
available phosphoric acid of bone is nevertheless not so 
readily utilizable by plants as " back-gone," or true re- 
verted phosphoric acid (dicalicum phosphate), which is 
produced by the direct action of lime or of tricalcium phos- 
phate upon soluble phosphoric acid (monocalcium phos- 
phate). 

304. Bone tankage. — Bone tankage contains widely 
varying percentages of phosphoric acid and nitrogen, 
ranging from 9 to 20 per cent of the former and usually 
from 4 to 8 per cent of the latter. 

What has been said of steamed bone applies to the tank- 
age produced by subjecting the waste bones of slaughter- 
houses and meat markets to the action of superheated 
steam. It is not infrequently the case that as much as 
one-half of the total phosphoric acid of such tankage is 
rendered soluble upon treatment in the conventional 
manner with neutral ammonium citrate solutions at 65° C, 
and it hence appears in the statement of the analysis as 
reverted phosphoric acid. What has been said of the use 
of bone in the previous section applies equally to the prac- 
tical employment of tankage. 

305. Fish as a source of phosphoric acid. — The refuse 
fish from the menhaden oil factories often contain, in 
addition to the 6 to 8 per cent of nitrogen, from 5 to 7 per 
cent of phosphoric acid. Fish heads and skeletons from 
fish works are often still richer in phosphate. Such fish 
wastes are often dried, ground, and sold directly to farm- 
ers ; they are also introduced into commercial fertilizers, 



NATURAL PHOSPHATIC FERTILIZERS 173 

especially in the manufacture of the goods sold under the 
name of " fish and potash." 

306. The nature of floats. — The name " floats " was 
given originally to an especially fine dust product which 
was formed in connection with the ordinary grinding of 
phosphate rock, but it is now often applied to any finely 
ground, unacidulated tricalcium rock phosphate. 

307. Soils on which to use floats. — This phosphate 
is especially applicable on peat or muck soils, as has been 
abundantly demonstrated in the course of the experiments 
on the renovation of the acid peat (Hochmoor) soils of 
northern Germany. Next to peat and muck soils, this 
material is useful on such upland soils as are exceptionally 
rich in acid vegetable matter. The profitable use of such 
phosphates has been especially pointed out by Hopkins in 
his work with the black soils of the Illinois corn belt. This 
phosphate is much less applicable on light, open, sandy, 
and gravelly soils than on those previously mentioned. 

308. The action of manure on floats. — According to 
pot experiments by Hartwell and Pember 1 and to ex- 
periments by The. Remy, 2 the mixing of the raw trical- 
cium phosphate with stable manure and decomposing 
materials does not materially increase its efficiency. In 
fact, the field experiments at the Ohio station which have 
been frequently cited elsewhere to prove the contrary 
were not conducted in such a manner as to furnish posi- 
tive evidence on this point either pro or con. It still 
remains to be conclusively demonstrated that floats are 
rendered more effective by being introduced either into 
the manure directly or by scattering them in the gutters 
behind the farm animals. 

1 Bulletin 151, R. I. Station. 

2 Bonn. Landw. Jahrb., 40, 559-611 ; Abs. Chem. Abstracts, 6, 1048. 



174 FERTILIZERS 

309. How floats should be used. — It is true of floats, 
as of other rather insoluble phosphates, that the best way 
to apply them is to incorporate them thoroughly with the 
soil ; for their availability is affected not only by the car- 
bonic acid brought into the soil by the rain and produced 
therein by the decay of vegetable matter, and by contact 
with acidic matter in the soil, but also by the nitric acid 
resulting from active nitrification. 

Floats are obviously most applicable to those plants 
which have a long season of growth, and least of all for 
such garden or trucking plants as must be pushed rapidly 
to maturity. In the latter case the crops must not only 
reach the market at the earliest possible moment, but the 
growth must be rapid in order that they may be tender and 
acceptable to the consumer. Again, floats are less ap- 
plicable for those plants which possess a low feeding 
power for phosphoric acid, such as the turnip, cabbage, 
and certain other similar plants, than for crops possessing 
a greater feeding power, as, for example, Indian corn, 
millet, clover, and certain grasses. Indeed, this difference 
in the requirement for readily available phosphoric acid 
has been well established by field experiments at Rotham- 
sted, by many European experimenters, and by Brooks 
and others in the United States. 1 Nevertheless, it is 
claimed that certain of the cruciferous plants can utilize 
raw phosphates better than either the oat or vetch can 
utilize them. 2 

310. Liming in connection with the use of floats. — 
The advice is often given never to lime land to which 
floats are to be applied on the ground that the lime, if 
freshly burned or hydrated, will absorb carbonic acid 

1 See Buls. 114 and 118 Agr. Expt. Sta. of the R. I. State College. 

2 Centralb. f. Agrikulturchemie, 39 (1910), 495. 



NATURAL PUOSPHATIC FERTILIZERS 175 

which might otherwise serve to attack the floats and 
render them more available. Another reason often given 
is based upon the known greater solubility of calcium 
carbonate than of tricalcium phosphate in carbonic acid. 
On this account the carbonic acid would be expected to 
be utilized in dissolving calcium carbonate, before it would 
attack the tricalcium phosphate to an appreciable ex- 
tent. Admitting that this might be sound advice as 
concerns a soil already well supplied, naturally or artifi- 
cially, with reasonable amounts of calcium carbonate, 
it does not, nevertheless, apply in all cases on such soils 
as are naturally deficient in calcium carbonate, especially 
if they are of a quite acid character. In order to make 
this point plain, it should be stated that a soil may be so 
acid that given varieties of plants will not thrive well 
upon it, and hence no matter how much phosphoric acid 
is made available by the action of carbonic acid, nitric 
acid, or otherwise, the plants cannot utilize it, because 
another factor has become the one which limits growth. 
Under such circumstances, therefore, enough lime must 
be applied to make the soil a suitable habitat for the 
plant, even though upon theoretical grounds, and with- 
out reference to the plant to be grown, the omission of 
lime would seem to be advisable. If, on the contrary, 
plants are grown which, like golden millet, serradella, and 
certain lupines, thrive well on acid soils, the advice about 
avoiding the use of lime, even on moderately acid soils, 
might nevertheless be sound. (See Fig. 15.) 

311. Apatite or phosphorite. — The terms "apatite" 
and " phosphorite" have come to be used interchangeably, 
although the latter is the term preferred for commercial 
purposes. 

Distribution in soils. — Apatite is a phosphate which is 



176 



FERTILIZERS 






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a § as 

a * ^ 

£ oi.SP 



- S 

1*3 



fe ft 



CQ 



NATURAL PIIOSPTIATIC FERTILIZERS 177 

widely distributed in minute crystals in most soils, and 
especially in rocks of igneous origin. This phosphate 
has probably been the source of the phosphorus in the 
organic matter, and in other combinations, in most soils 
of such derivation. It has been assumed that in many 
cases, minute crystals of apatite are formed in the soil 
under normally existing conditions, although laboratory 
experiments made in the attempt to produce them, in a 
wet way, have thus far failed. 

312. The chemical composition and occurrence of 
apatite. — The pure crystals of apatite are usually blue 
or green, although they may be gray, white, and 
transparent. The mineral, if pure, is a fluor-apatite 
corresponding closely to the formula 3 Ca 3 P20 8 + CaF 2 . 
Occasionally, however, the fluorin is wholly or partially 
replaced by chlorin, in which case the apatites are lighter 
in color and are designated as chlor-apatites. The pure 
fluor-apatite contains about the equivalent of 92.25 per 
cent of tricalcium phosphate, and 7.75 per cent of calcium 
fluorid. A sample of Norwegian apatite examined by 
Voelcker was found to have the following composition: — 

Per Cent 

Tricalcium phosphate 90.07 

Calcium chlorid 6.13 

Calcium fluorid ■ . 2.54 

Oxid of iron . . . . . i ■ . . . 0.29 

Alumina . 0.38 

Potash and soda 0.17 

Water 0.42 

Apatites are found in several places in Renfrew and 
Lawrence counties in Canada, where beautiful large 
crystals occur, likewise in the Province of Estramadura, 
Spain. They also occur in Portugal, Norway (near Chris- 
tiania), and elsewhere. Apatite is often found in veins 



178 FERTILIZERS 

mixed with quartz, as nodules in certain sand-stones, in 
carboniferous slates, and as cementing material in rocks. 
Many of the apatites occur in massive or amorphous forms. 

For several years the apatites of Canada, containing 
the equivalent of 80 to 86 per cent of tricalcium phos- 
phate, those from Norway, containing the equivalent 
of 70 to 90 per cent of tricalcium phosphate, and the 
deposits in Spain, containing the equivalent of from 70 
to 85 per cent of tricalcium phosphate, were worked quite 
extensively ; but these phosphates have since been largely 
replaced by those from Algeria, Florida, Tennessee, and 
from many other sources. At present renewed interest in 
them is being awakened in view of their possible utilization 
by the process of Palmaer (see Section 340) . 

When apatite is reduced to a powder and is subjected 
to the action of pure water, the resulting solution gives 
an alkaline reaction with phenolphthalein or litmus, 
whereas the ordinary tricalcium phosphates yield an acid 
solution with the same indicators. The solubility of 
apatite is about seven times as great in a saturated solu- 
tion of carbon dioxid as in water, but even then more lime 
than phosphoric acid is dissolved. The presence of even 
a small amount of carbonic acid in solution also increases 
its solubility. 

313. Wagnerite. — The mineral Wagnerite is a mag- 
nesium fluor-apatite corresponding to the calcium fluor- 
apatite. There exists also a corresponding ferrous salt 
known as triplite, but neither of these is of importance as 
a soil mineral or from the fertilizer standpoint. 

314. Coprolites. — The term " coprolite " from two 
Greek words meaning " dung " and " stone " was given 
by Buckland to certain peculiarly shaped stones found in 
the Lias marls chiefly at Lyme-Regis and also near Bristol, 



NATURAL PHOSPHATIC FERTILIZERS 179 

England, which were said to resemble fossil fir cones. 
They are from 2.5 to 4 or even in extreme cases 8 inches 
in length, somewhat flattened, and ranging in color from 
ash gray to black. The coprolites were found in deposits 
with remains of the Ichthyosaurus and the bones and 
teeth of fish, which coupled with the fact that their struc- 
ture resembled that of fossilized animal excreta, led to 
the belief that they were chiefly the excreta of reptiles of 
the extinct group of saurians. The term " coprolites " was, 
however, also applied to phosphates which are now known 
to be of undisputed concretionary character. The latter 
have also been called pseudo-coprolites in order to dis- 
tinguish them from those of faecal origin. 

Coprolites are by no means confined to England, for they 
occur in France, Russia, and elsewhere. 

The concretionary origin is supposed to be the result 
of the replacement of the carbon dioxid of calcium car- 
bonate by phosphoric acid, in the presence of moisture 
and vegetable matter. 

The coprolites are usually associated with considerable 
calcium carbonate, also with calcium fluorid, oxids of 
iron, alumina, silica, and small amounts of organic matter. 
They usually contain from 50 to 60 per cent of tricalcium 
phosphate. 

315. Phosphatic guanos. — Where birds deposit large 
quantities of excreta in humid locations the material 
gradually loses its nitrogen until the residues finally be- 
come mineral phosphates. 

The Island of Lobos yields a guano with only from 2 to 
3 per cent of nitrogen. This represents a stage between 
the true guano with a high nitrogen content and these 
true phosphatic guanos. These phosphates often con- 
tain, as might be expected, traces of nitrogen and alkalies, 



180 FERTILIZERS 

but the amounts are too small to be of any practical 
account. 

Such guanos often contain from 70 to 80 per cent of 
tricalcium phosphate and usually but small quantities of 
iron and aluminum. These characteristics, and the ease 
with which they can be pulverized, make them well 
adapted to the manufacture of superphosphate. 

The phosphatic guanos known as Aruba, Navassa, 
Sombrero, and Curacao are found in the West Indies. 
The Mejillones guano comes from Bolivia, and large quan- 
tities have been found on the Baker, Abrolhos, Christmas 
and Oceanic islands in the Pacific, and elsewhere. Some 
of these guanos have an average content of 80 to 85 per 
cent of tricalcium phosphate. Many of the original 
deposits have been exhausted, but the phosphate is still 
being imported from the Oceanic and Christmas islands, 
and from a large number of other islands of the Pacific. 

Clipperton Island in the open sea off the coast of Brazil 
is covered with a bed of phosphatic guano six feet deep. 
It contains from 83 to 86 per cent of tricalcium phosphate 
and only traces of iron and alumina. 

316. Nassau or Lahn phosphate. — The so-called 
Nassau or Lahn phosphate is found in Germany and 
these deposits were worked extensively following their 
discovery in 1864. They contain from 35 to 70 per cent 
of tricalcium phosphate ; but such large amounts of iron 
and alumina are present as to make them objectionable 
for the manufacture of superphosphate. Germany has 
at present practically no workable phosphate deposits. 

317. French, Belgian, and Portuguese phosphates. — 
The Departments of Pas de Calais, Somme, and Oise, in 
France, contain valuable deposits belonging to the Cre- 
taceous period ; and many other sections of the country 



NATURAL PIIOSPIIATIC FERTILIZERS 181 

also contain very extensive deposits, though often in thin 
beds. 

Phosphate deposits at Mesvin and at Cipley near Mons, 
Belgium, have been worked extensively. The lower 
grades from these deposits contain from 25 to 30 per cent 
of tricalcium phosphate. The better grades, which occur 
chiefly in pockets, contain from 45 to 60 per cent of tri- 
calcium phosphate. This phosphate is light brown and 
has practically the appearance of oolite. It crumbles 
easily and owing to its peculiar structure it has at times 
been imported into the United States in small amounts 
for use as a drier in mixed fertilizers, in order to make 
them more drillable. 

Other phosphate deposits exist in the district of Liege 
and elsewhere in Belgium. 

Phosphates somewhat similar to those of Cipley have 
been found in France, Portugal, and elsewhere and, al- 
though they are often quite rich in tricalcium phosphate, 
they contain clay and marl in quantities objectionable 
from the standpoint of the superphosphate manufacturer. 
An exception is however afforded by the Somme phos- 
phates of northern France which are richer in tricalcium 
phosphate, and contain less iron and aluminum oxids. 
In utilizing them for the manufacture of superphosphate 
it is considered desirable or necessary to employ hot 
rather than cold sulfuric acid. 

318. The phosphates of Russia and Northern Africa. — 
In Russia there are large numbers of phosphate deposits, 
the best of which are in central Russia. They are dis- 
tributed over an area estimated at 50,000,000 acres. 

One of the chief sources of phosphate for Europe, at 
present, is the great deposit supposed to stretch practically 
across the northern part of the continent of Africa, though 



182 FERTILIZERS 

Morocco has not as yet been carefully examined. The 
centers of export are Algeria and Tunis from which ap- 
proximately two millions of tons are now shipped annually. 

The amount of tricalcium phosphate usually present 
in the material as exported is about 60 per cent, but by 
careful selection it may run as high as 70 per cent. 

The beds thus far explored in Egypt yield a phosphate 
containing only from 40 to 50 per cent of tricalcium phos- 
phate, which is too low for present profitable exportation. 
These deposits underlie the Eocene ; and the phosphate- 
bearing strata usually range from 7 to 10 feet in depth. 

One great advantage of these phosphates is that they 
contain only little iron and alumina. When used in an 
unacidulated form in comparison with the Florida phos- 
phate, on the Hochmoor (acid peat) soils of northern 
Germany, they have been reported as being superior to 
the American product. 

319. The phosphates of South Carolina. — Until within 
the last twenty years the main source of phosphate for 
the United States was South Carolina. The chief supply 
for Europe came also from the same source until the dis- 
covery of the high grade African deposits. Many of 
these phosphates are essentially nodular and belong at 
the bottom of the Eocene period ; others consist of phos- 
phatic limestones alternating with the nodular deposits. 
The material resembles somewhat that at Cipley in Bel- 
gium. Associated with the phosphates, in the beds of 
marl, are teeth and bones of sharks. The phosphate, 
however, has been redeposited from solution in carbonic 
acid and in organic acids, and is still being formed. 

The so-called " river " phosphate was secured by dredg- 
ing the bottoms of rivers, whereas the usual methods of 
mining prevail in connection with the land phosphates. 



NATURAL PHOSPLTATIC FERTILIZERS 183 

The former contain usually about 60 per cent of trical- 
cium phosphate, but they are preferable for the manufac- 
ture of superphosphate to the richer (70 to 80 per cent) 
land phosphate on account of their containing less iron 
and aluminum oxids. 

320. The Florida phosphates. — The discovery of 
phosphates of the Oligocene period in Florida in 1887, 
followed by their extensive exploitation, focused the 
attention of the entire world upon them. 

The black, river, pebble phosphate containing 60 to 70 
per cent of tricalcium phosphate was formerly dredged in 
large quantities from beds of streams, but such mining in 
the Peace River district has now been abandoned. 

The land pebble phosphate, which bears much resem- 
blance to calc-sinter, is found in Florida in large quantities ; 
and the output has reached as much as 1,250,000 tons per 
annum. It is consumed chiefly in the United States. 
It contains from 66 to 75 per cent of tricalcium phosphate 
and an average of 2.3 per cent of iron and aluminum oxids, 
though the latter usually fall below 2 per cent. The 
masses are rounded, flattened and of a yellowish to white 
color and occur associated with occasional stringers of 
quartz sand. The deposits resemble gravel beds in cer- 
tain respects. 

The better grades of land phosphate, to which the terms 
" rock " and "bowlder " phosphate are applied, vary less 
in composition than the pebble phosphates and are sold 
on a guaranty of 77 per cent of tricalcium phosphate, but 
they not infrequently contain as much as 80 per cent. 
This is much in excess of the amount in the South Carolina 
phosphate. They frequently, however, contain as much 
as 6 per cent of iron and aluminum oxids which is a highly 
objectionable feature. 



184 FERTILIZERS 

Soft phosphate. — The Florida " soft " phosphate, con- 
taining from 25 to 70 per cent of tricalcium phosphate 
and 3 to 7 per cent of iron oxid and alumina, is usually 
associated with such large quantities of calcium carbonate 
or earthy matter, as to render it unsuitable for the most 
economical manufacture of superphosphate. For this 
reason it has been ground and utilized to a considerable 
extent for direct application to the land, and likewise as 
a drier in the manufacture of commercial fertilizers. 

321. The Tennessee phosphates. — Upon the dis- 
covery of the great phosphate deposits of Tennessee in 
1894, following closely upon those in Florida, it was con- 
sidered that inexhaustible supplies were at hand; the 
quantity mined has, however, reached from two to three 
million, tons per annum and it is now estimated by the 
U. S. Geological Survey that the exhaustion of these deposits 
will be accomplished in another generation, if the mining 
increases at as great a rate as is to be expected. 

322. Phosphates of the Western States. — In view of 
the rapid exhaustion of the phosphate beds of the eastern 
United States, the recent discovery of high grade phos- 
phate fields in Idaho, Wyoming, and Montana, which 
are now believed to be the greatest thus far discovered in 
the world, is hailed with great satisfaction by those in- 
terested in the future prosperity of the United States. 
In each of the nine townships thus far examined it is 
estimated that there are not less than 60,000,000 tons of 
high grade phosphate rock, and in one of the townships 
the estimate reaches 293,000,000 tons. 

The preceding estimates do not embrace 34,000 acres 
of Montana phosphate beds previously withdrawn from 
the lands opened for settlement. These figures are es- 
pecially significant when one recalls that but about 39,000- 



NATURAL PHOSPHATIC FERTILIZERS 185 

000 tons of phosphate rock have thus far been mined in 
the United States. 

Certain of these western deposits are situated reason- 
ably near great copper smelters which are capable of pro- 
ducing enormous quantities of sulfuric acid as a cheap by- 
product, so that the conditions are especially favorable 
for the manufacture of acid phosphate or of other even 
richer products. In the case of some of the latter the cost 
of transportation, per unit of phosphoric acid, would be 
but one-third of the cost in ordinary acid phosphate. 

323. Occurrence and composition of certain aluminum 
phosphates. — Aluminum phosphate, associated with some 
iron phosphate, is found on the Islands of Grand Conne- 
table, a French possession on the coast of French Guiana ; 
on the Island of Redonda (where the mineral redondite 
occurs) , near the Island of Montserrat in the British West 
Indies ; and on the Islands of Alta Vela, Sombrero, and 
Navassa. The material from the Island of Redonda often 
contains as much as 35 to 36 per cent of phosphoric acid, 
combined almost wholly with alumina. It may never- 
theless contain in some cases as little as 20 per cent of 
phosphoric acid. The phosphates from Alta Vela, Som- 
brero and Navassa, contain about 22, 31, and 31 per cent 
of phosphoric acid, respectively. 

Wavellite. — The mineral Wavellite is a crystallized 
aluminum phosphate (3 A1 2 3 • 2 P 2 5 • 12 H 2 0) which, 
though possibly formed in a wet way, is supposed by 
certain writers not to be generally present in soils. 

324. Roasting increases the efficiency of aluminum 
phosphate. — The efficiency of these phosphates is greatly 
increased by subjecting them to a roasting process. This 
fact is not new but it has been recently well shown in 
trials of the roasted and unroasted product, at the experi- 



186 FERTILIZERS 

ment station of the Rhode Island State College, 1 and later 
in the course of experiments by Fraps. The Rhode Is- 
land experiments have shown in a most striking manner 
the effect of slaked lime in increasing the crop-producing 
efficiency of the roasted, in contrast with the unroasted, 
Redonda phosphate. Furthermore, this effect con- 
tinues for several years after the last application of each 
substance is made to the soil. (See Figs. 16 and 17.) 

325. The solubility of artificial aluminum phosphate. — 
The solubility of artificial aluminum phosphate appears, 
according to Gerlach, not to be increased by the presence 
of carbon dioxid in solution, even in the presence of lime 
and magnesia, but its solubility is greatly increased by 
sodium and potassium hydroxids and in a lesser degree 
by free mineral acids. As concerns oxalic and citric acids, 
they differ but little in their solvent action upon the phos- 
phoric acid of aluminum phosphate, and both are far 
superior in this respect to acetic acid. The presence of 
aluminum hydroxid while lessening the solvent action of 
acetic acid had no effect upon the action of citric and oxalic 
acids. 

According to Schneider 2 both aluminum chlorid and 
aluminum sulfate, which give acid solutions, increase the 
solubility of aluminum phosphate. 

The action of water upon several artificial preparations 
of aluminum phosphate of varying degrees of basicity, 
has been determined by Cameron and Hurst, 3 from which 
it appears that the total quantity of phosphoric acid dis- 
solved, increased with the volume of water ; but that the 
concentration of the solution became less as the quantity 

1 Bulletins Nos. 114 and 118. 
2 Zeit. anorg. Chemie., 5 (1894), 87. 
3 Jour. Am. Chem. Soc., 26 (1904), 385. 



NATURAL PHOSPHATIC FERTILIZERS 



187 



o 

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•S d 



5 (CO 

p "S -2 



d o 



co d 

ft ft a 



3 *g 



pq 





w se 



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g o g 



■G 43 

to a 



- « ° d 



3 <p 

d S 

<S CO 
43 

CO 

CO <u 



£ e 



M 



188 FERTILIZERS 

of the water was increased. A greater removal of phos- 
phoric acid than of aluminum was shown, analogous to 
the case of the iron phosphate (Section 327). The same 
investigators found that aluminum phosphate behaves, 
toward solutions of potassium chlorid, in a similar manner 
as the calcium and iron phosphates ; or in other words, 
that with an increase in the concentration of the chlorid 
the phosphoric acid in the solution became less. Similar 
results were noted also with potassium sulfate and with 
sodium nitrate. It appears therefore, that, like iron 
phosphate, the solubility of aluminum phosphate is af- 
fected much less by neutral salts than by acid or alkaline 
solutions. 

326. Iron phosphate formed in soils. — The phosphate 
of iron is formed wherever dissolved phosphate is brought 
in contact in the soil with oxid of iron. 

Phosphates of iron are often found associated with peat 
deposits, where through the reducing action of vegetable 
matter ferrous phosphate (the phosphate of the protoxid 
of iron) often occurs in large quantities. 

Vivianite. — A ferrous phosphate, known as Vivianite 
(Fe 3 (P0 4 )2 • H 2 0), occurs as a mineral, but it has not 
yet been proved to be common in soils, although this 
has been assumed by some writers. 

327. The solubility of artificial ferric phosphate. — 
Experiments have been made by Lachowiez * with arti- 
ficially prepared ferric phosphate which contained phos- 
phoric acid considerably in excess of that (47.02 per cent) 
corresponding to the formula FeP04 . Such phosphate, 
after various treatments with hot or boiling water, yielded 
acid solutions containing but minute quantities of iron. 
The quantity of phosphoric acid in the residues after the 

1 Monatsh., 13 (1892), 357, cited from Cameron and Bell, 



NATURAL PHOSPHATIC FERTILIZERS 189 

various treatments was lowered from 48.14 per cent to a 
minimum of 46.33 per cent. At the same time the per 
cent of Fe 2 3 was raised from 48.97 (the formula 
FeP0 4 requires 52.98 per cent) to a maximum of 61.98 
per cent. After a considerable number of days a con- 
dition of equilibrium is reached between the solid and the 
solution. In order therefore, to effect a further removal 
of phosphoric acid fresh quantities of water are required. 
It has been inferred that it is possible, by a sufficient 
number of successive treatments with water, to remove 
all of the phosphoric acid, in which case only ferric hy- 
droxid would remain. These results have been confirmed 
by Cameron and Hurst, who also experimented with a 
basic phosphate without however finding that it mate- 
rially altered the character of the results. The presence 
of neutral salts, at least in certain concentrations, has no 
material effect upon the amount of phosphoric acid brought 
into solution, whereas salts having an alkaline reaction, 
as for example alkaline carbonates, increased the solvent 
power of the solution for the phosphoric acid of the ferric 
phosphate. The solubility was found to be especially 
marked in the case of the presence in solution of the car- 
bonates and acetates of sodium and potassium. The 
same is also true of disodium phosphate, notwithstanding 
the probable formation in this case of a common ion. 

Iron phosphates are soluble in alkali hydroxids and less 
readily in solutions of free mineral acids. Their solubility 
is also increased by the presence of salts which when hy- 
drolized yield alkaline solutions. 

It was found by Gerlach 1 that oxalic acid was a more 
effective solvent of artificial iron phosphate than citric acid 
and that this was even much superior to acetic acid. In 

i Landw. Vers.-Sta., 46 (1895), 201. 



190 FERTILIZERS 

the presence of free iron hydroxid, acetic acid had no ap- 
preciable solvent effect on the iron phosphate. Citric 
acid had far less effect under the same condition than other- 
wise, whereas the solvent action of oxalic acid was not in- 
fluenced. 

It was found by Cameron and Bell that there was a great 
and unexpected increase in acidity when iron phosphate 
was treated with solutions of certain neutral salts. This 
they attribute to selective absorption whereby the basic 
part unites with the solid residues leaving free acid in 
solution. 

It is asserted that the presence of calcium carbonate 
may increase the solubility of iron phosphate, but in this 
particular calcium bicarbonate is far more effective. 



CHAPTER XVI 

MANUFACTURED PHOSPHATES AND STUDIES OF SOLUBILITIES 

In recent years, owing to the great demand for phos- 
phatic fertilizers and on account of the wide recognition of 
the necessity, for many purposes, of having them readily 
available, the ground raw and steamed bone have been 
very largely replaced by the artificially prepared phos- 
phates. 

328. The manufacture of basic slag meal. — Basic slag 
meal (not to be confused with non-phosphatic or but 
slightly phosphatic slags of ordinary blast furnaces) is a 
waste product of the manufacture of steel from iron 
phosphate by the modification of the Bessemer process 
developed by Thomas and Gilchrist of England. This 
consists in passing air through a mixture of molten iron 
phosphate and lime, in a large pear-shaped converter lined 
on the bottom and sides with a mixture of tar and lime, 
or magnesian lime. The tar is employed in order to 
make the lime adhere to the converter. A current of 
air is then forced through the mass until spectroscopic 
observations of the gases evolved show that the oxida- 
tion is complete. The slag formed by the union of the 
oxids of phosphorus and of silicon with lime, is then 
poured off by decanting the converter, after which the 
steel is drawn off below. After pulverization the slag 
meal is sold under the name of " basic cinder," " basic 
slag meal," or " Thomas phosphate powder." 

In the earlier days of the manufacture of basic slag meal 

191 



192 FERTILIZERS 

it was found to vary greatly in its availability to plants, 
dependent upon the works from which the material came, 
and certain works in particular had the reputation of 
turning out a product having a very low efficiency as a 
fertilizer. 

329. The influence of silica on the efficiency of basic 
slag. — ■ It was finally discovered by Hoyermann of Han- 
nover, Germany, and later fully established by the work 
of others, that this difference in availability was caused by 
variations in the amounts of silica which were present, 
and that frequently by the introduction of extra silica 
the efficiency of the resulting slag meal could be greatly 
increased. In consequence of this discovery there is now 
usually less difference than formerly in the availability 
of the European product, which at present constitutes the 
chief source of supply for the United States. 

330. The range in composition of low and high grade 
basic slag. — There is produced in certain works in Eng- 
land a grade of basic slag meal with a very low content 
of phosphoric acid ranging usually from 12 to 14 per cent. 
There are on the other hand basic slag meals on the market 
containing from 25 to 28 per cent, but the grades more 
commonly brought into the United States usually contain 
from 16 to 19 per cent of phosphoric acid. It has been 
asserted that in some cases the percentage of phosphoric 
acid is raised by the introduction of tricalcium phosphate 
into the converter, with the result that the percentage of 
phosphoric acid is increased at the expense of the avail- 
ability of the product. Certain Belgian exporters claim, 
nevertheless, that they can furnish slag meal, with the 
higher percentages of phosphoric acid, which has not been 
fortified in this manner. 

331. The German methods of determining availability. 



MANUFACTURED PHOSPHATES 193 

— The agricultural experiment stations of Europe busied 
themselves for some years in the attempt to find a labo- 
ratory method of treatment, capable of indicating essen- 
tially the same degree of availability of basic slag meal as 
was shown by experiments with plants. The method in 
use prior to 1899, consisted in extracting the material, under 
definite conditions, with an acid solution of ammonium 
citrate, but this was then replaced by a 2 per cent solu- 
tion of citric acid, which is used in the present official 
German method. The purchase of basic slag meal on 
analysis, by this method, is advisable as an insurance 
against the introduction of ordinary tricalcium phosphate 
as an adulterant. 

332. The degree of fineness. — The degree of fineness, 
and the total content of phosphoric acid, also furnish valu- 
able criteria of the value of basic slag meal. In fact 80 
per cent of it should readily pass through a sieve having 
100 meshes to the linear inch. 

333. The chemical composition of basic slag. — In 
addition to phosphoric acid, basic slag usually contains 
calcium, magnesium, iron as ferrous and ferric oxids, cal- 
cium sulfid, and small quantities of oxids of manganese, 
vanadium, silicon, and sulfur. Such amounts of metallic 
iron as are present are usually separated by a magnet dur- 
ing the process of pulverization. The composition of the 
final product varies according to the composition of the 
lime, iron ore, and other materials added in the converter. 

Per Cent 

Calcium oxid 40-60 

Phosphorus pentoxid (Jf 2 O s ) .... 10-20 

Iron oxid 10-20 

Silica 5-15 

Manganese oxid 3-6 

Magnesium oxid 2-6 

Alumina 1-3 

o 



194 FERTILIZERS 

In general the composition of basic slag meal may be con- 
sidered as ranging between the preceding limits. 

The amount of free lime in basic slag meal is now less 
than formerly, owing to the greater amount of silica in- 
troduced into the converters. It usually ranges from 1 to 
6 per cent, though the upper limit, recently determined 
by James Hendrick l in seven lots of basic slag with rather 
low phosphorus content which were sold in England, was 
only 3.08 per cent, as shown by the lime dissolved by long 
shaking with a 10 per cent sugar solution. The amount 
of lime capable of acting as a base, as determined by Hen- 
drick in these slags, ranged from 13.6 to 28.3 per cent. The 
method used for this determination was distillation with 
ammonium sulfate and measurement of the equivalent, 
by the ammonia liberated. The introduction of the extra 
silica into the converter obviously increases the amount of 
calcium silicate present, and lessens the quantity of free 
lime. 

334. As to the constitution of basic slag. — In case 
basic slag is cooled slowly, certain flat, square, plate crys- 
tals are formed, which upon analysis have been found 
to be tetracalcium phosphate, the structure of which as 
compared with tricalcium phosphate is shown below : — 

O 

Ca< >P-0-Ca-0-P< >Ca 

tricalcium phosphate 

o o 

Ca< >P-0-Ca-0-Ca-0-P< >Ca 

tetracalcium phosphate 
1 Jour. Soc. Chem. Ind., 28, 776. 



MANUFACTURED PHOSPHATES 195 

The tetracalcium phosphate, if reacted on by weak acids, 
yields two molecules of calcium oxid to the acid and is 
transformed into dicalcium phosphate. 1 

It was long supposed that basic slag was strictly a tet- 
racalcium phosphate, yet it was difficult to account for 
all of the lime on that supposition, even with due allow- 
ance for silica, sulfur, and for the lime which can be looked 
upon as " free " lime. Further doubt is thrown upon the 
basic slag being tetracalcium phosphate, by the fact that 
the flat crystals just mentioned are not found in slag which 
is rich in silica. The crystals usually formed under such 
circumstances are long hexagonal needles, pale green, or 
blue, in color, the presence of which would more readily 
account for the peculiar fracture of basic slag than the 
crystals of tetracalcium phosphate. These needle-shaped 
crystals have been shown by Stead to have the composi- 
tion (CaO)5P 2 5 Si02 which gives approximately 11 per 
cent of silica, 29 per cent of phosphoric acid, and 56 
per cent of lime. When these crystals are subjected to 
the action of carbonic acid or dilute citric acid their 
solubility is found to accord far more nearly with that 
of basic slag meal, than the crystals of tetracalcium 
phosphate. 

335. The practical use of basic slag meal. — Basic 
slag meal becomes especially available in the presence 
of considerable moisture and hence it usually acts well 
on clayey, soils ; it also improves their physical condi- 
tion because of the presence of calcium oxid and 
calcium carbonate. 

On peat or muck soils which are acid, basic slag meal has 
also been employed with splendid effect. Its use on sandy 

1 O. Forster, Zeit. f. angew. Chemie, 18, 22 (1892) ; Jour. Soc. Chem. 
Ind., p. 460 (1892), cited from Hendrick. 



196 FERTILIZERS 

soils is followed by excellent results except in case of 
extreme drought. 

The ideal soils on which to use basic slag meal are acid 
uplands, for benefit to them not only results from the phos- 
phoric acid, but also to a moderate degree from the free 
lime, and from the lime present as carbonate, silicate, and 
phosphate. This is by virtue of gradually lessening the 
soil acidity and consequently postponing the time when 
further liming will be necessary. A single or several 
repeated applications of basic slag meal will often bring 
in clover and create conditions favorable to the growth of 
timothy, barley, and other plants; whereas the use of 
acid phosphate or of double superphosphate may, under 
the same conditions, make the situation even slightly 
worse. If applied to acid pasture soils, basic slag meal 
aids in bringing in white clover, and thus materially adds 
to their value for grazing purposes. (See Fig. 18.) 

336. Care in mixing basic slag with certain other ma- 
terials. — Care must be taken not to mix basic slag meal 
with organic nitrogenous fertilizers in case they are to be 
stored before their application, especially if they absorb 
much moisture, for some loss of nitrogen as ammonia may 
result. It is equally important not to mix basic slag with 
acid phosphate or double superphosphate, for some of the 
lime will be neutralized thereby and hence lose much of its 
immediate corrective value. At the same time the lime 
would tend to cause the reversion of some of the soluble 
phosphoric acid, thus rendering the superphosphates less 
valuable, particularly for the purpose of top-dressing. 

If basic slag is mixed with sulfate of ammonia, the free 
lime is sure to liberate some of the ammonia, and at the 
same time the lime will be transformed into land plaster 
or gypsum and hence lose its capacity for correcting the 



MANUFACTURED PHOSPHATES 



197 




198 FERTILIZERS 

condition of acid soils. This reaction is shown by the fol- 
lowing equation : — 

(NH 4 ) 2 S0 4 + CaO = CaS0 4 + NH 3 + H 2 

sulphate of ammonia lime gypsum ammonia water 

For the reasons given above, basic slag meal should 
usually be applied to the soil by itself, though it can be 
mixed with nitrate of soda, nitrate of potash, and with the 
German potash salts without fear of loss or of the dete- 
rioration of any of the ingredients of the mixture. 

337. Artificial basic slag meal. — On account of the 
popularity of basic slag meal and of the consequent in- 
creased demand for it, many attempts have been made to 
produce a similar product by a direct process of manufac- 
ture. To this end apatite and other phosphates have been 
fused with silica and lime whereby a strictly basic product 
is said to result, resembling in many respects genuine basic 
slag meal. Such products have been found to be soluble 
by the usual method of treatment with ammonium citrate, 
to the extent of 90 per cent of the phosphoric acid. 

These products have been given various names, and they 
have also been sold as (< artificial " basic slag. 

338. Wiborgh phosphate. — This product has been 
prepared by fusing together feldspar, sodium carbonate, 
and phosphorite. It is also said to have been made with- 
out the introduction of the feldspar. The fusion is made 
at from 900° to 1000° C. The final product has been rep- 
resented by the formula : 2 Na 2 • 10 CaO • 3 P 2 5 . The 
phosphoric acid is soluble to the extent of 21 to 27 per 
cent in a solution of ammonium citrate ; and it has been 
found to compare favorably with superphosphate and 
basic slag meal. It is especially adapted to the peat 
soils of Sweden, where it has been chiefly used. It has 



MANUFACTURED PHOSPHATES 199 

now been superseded by the Palmaer phosphate, which is 
produced more economically. 

339. Wolter's phosphate. — Another artificial product 
quite similar to the preceding is made by fusing in a re- 
generative furnace 100 parts of powdered phosphorite, 
70 parts of sodium sulfate, 20 parts of calcium carbonate, 
22 parts of sand, and 6 to 7 parts of coke. The molten 
material is first run into water, and is at last finely pul- 
verized. By this process the phosphoric acid is rendered 
almost wholly soluble in a 2 per cent citric acid solution. 
The phosphoric acid in this material has been found to be 
even more efficient than that in basic slag meal, and but 
slightly inferior to that in superphosphate. 

340. Palmaer Phosphate. — In the Palmaer process a 
solution of sodium chlorate or of sodium perchlorate is 
electrolyzed. The acid anode solution is then made to 
react on the raw phosphate, which it readily dissolves. 
Thereupon some of the alkaline cathode solution is 
added, as a result of which dicalcium phosphate is pre- 
cipitated as a fine crystalline powder. After this is 
separated by filtration, the remainder of the cathode 
solution is added to the filtrate, whereupon most of the 
lime in solution is separated as calcium hydrate. The 
remainder is then removed as carbonate by the intro- 
duction of carbonic acid. The electrolyte, thus regen- 
erated by the process, again enters the electrolyzing 
apparatus. 

The dicalcic phosphate thus produced contains 36 to 
38 per cent of phosphoric acid, 95 per cent of which is 
soluble in a solution of ammonium citrate. 

Experiments with this phosphate in Sweden, on sandy 
and on peat soils, have shown its direct and residuary effects 
to be on a par with those secured with superphosphate. 



200 , FERTILIZERS 

On peat soil the residuary effect of Palmaer phosphate has 
been found by Von Feilitzen to agree with acid phosphate 
but to be somewhat inferior to that secured with basic 
slag meal. By this process low-grade apatites can be 
utilized. 

341. Other artificial phosphates. — By heating a mix- 
ture consisting of equal parts of 55 per cent phosphoric 
acid and either ammonium sulfate or potassium sulfate, 
at 80° C. there results a pulverulent product. The fol- 
lowing illustrates the course of the reaction with potas- 
sium sulfate : — 

K 2 S0 4 + H3PO4 = KHSO4 + KH 2 P0 4 . 

This product contains 24 per cent of phosphoric acid, and 
27 per cent of potash. The corresponding product made 
by substituting ammonium sulfate for the potassium sul- 
fate, contains 25 per cent of phosphoric acid and 10.5 
per cent of nitrogen. A corresponding sodium salt cannot 
be prepared in this manner. On account of the acid 
character of this material, due to its containing 30 per 
cent of sulfuric acid, it may be mixed to advantage with 
basic slag meal, at least in so far as concerns the avail- 
ability of the phosphoric acid. It is also especially ap- 
plicable on calcareous soils. 

From low-grade calcium phosphate. — Another artificial 
product is prepared on a similar principle by the intro- 
duction of a low-grade calcium phosphate, too rich in 
calcium carbonate for profitable superphosphate manu- 
facture. By suitable processes of evaporation, filtra- 
tion, and desiccation an excess of sulfuric acid is 
avoided and there is produced a sulfo-phosphate con- 
taining 38 to 40 per cent of phosphoric acid, which is 
chiefly soluble. It also contains 31 to 33 per cent of 



MANUFACTURED PHOSPHATES 201 

potash and small quantities of sulfuric acid, lime, and 
other substances. 

From aluminum phosphate. — Redonda phosphate and 
other similar aluminum phosphates can be utilized, in a 
similar way, to make sulfo-phosphates of ammonia and 
aluminum sulfate, by fusing the phosphate with ammo- 
nium disulfate for from two to three hours. The re- 
action is as follows : — 2 A1P0 4 + (NH 4 ) HS0 4 + H 2 S0 4 = 
A1 2 (S0 4 ) 3 + 2 (NH 4 )HS0 4 • (NH 4 )H 2 P0 4 ). Practical diffi- 
culty arises in this treatment, due to the presence of 
aluminum sulfate, but this may be obviated by adding 
an equivalent amount of ammonium disulfate, whereupon 
a product is obtained which remains dry. The reaction 
is then as follows : — A1P0 4 + 3 (NH 4 )HS0 4 = A1(NH 4 ) 
(S0 4 ) 2 + (NH 4 )HS0 4 • (NH 4 )H 2 P0 4 . 

By the use of bisulfate. — A so-called " bisulfate-super- 
phosphate " has been prepared by treating Algerian phos- 
phate with bisulfate refuse from nitric acid works. If 
properly managed, a dry product results which contains 
from 7 to 8 per cent of soluble phosphoric acid. 

342. The preparation of superphosphates. — In order 
to secure a greater efficiency of phosphoric acid than is 
possible when it is in the state of tricalcium phosphate, 
the latter is treated with sulfuric acid. In this process 
two-thirds of the lime combines with sulfuric acid to form 
land plaster, or gypsum, which remains in the mixture 
with the monocalcium phosphate (soluble phosphoric acid) 
which is produced. The resulting mixture is called 
" superphosphate." If made from spent bone-black, it 
is given the name of " dissolved bone-black" ; if from 
bone, " dissolved bone " ; and if from mineral tricalcium 
phosphate, either " plain superphosphate " or " acid 
phosphate." The reaction is shown by the following 



202 , FERTILIZERS 

equation : — 

Ca ? (P0 4 ) 2 + 2 H 2 S0 4 = 2 CaS0 4 + CaH 4 (P0 4 ) 2 . 

tricalcium sulfuric calcium monocalcium 

phosphate acid sulfate phosphate 

In the practical application of the process, small quan- 
tities of free phosphoric acid, dicalcium phosphate, and 
tricalcium phosphate are present in the product. 

343. Treatment of bone with small amounts of sulfuric 
acid. — A few years ago much interest was awakened by 
a proposition to use only about half the usual amount of 
sulfuric acid, in the treatment of bone. By this means 
the cost of the treatment was greatly lessened, and yet 
the material produced was claimed to possess a very high 
degree of manurial efficiency. Such a product, because 
of its slight solubility, would, however, not be fully satis- 
factory for the top-dressing of either grass lands or grain 
crops. By this process only one-third of the lime would 
be removed from the tricalcium phosphate, as suggested 
below : — 

Ca 3 (P0 4 ) 2 + H 2 S0 4 = CaS0 4 + 2 CaHP0 4 . 

tricalcium sulfuric calcium dicalcium 

phosphate acid sulfate phosphate 

344. Free phosphoric acid in superphosphate. — If 
more sulfuric acid is used than is customary for the pro- 
duction of monocalcium phosphate, considerable free 
phosphoric acid is formed ; and by employing enough 
sulfuric acid to replace all of the lime, the following would 
be the course of the reaction : — 

Ca 3 (P0 4 ) 2 + 3 H 2 S0 4 = 3 CaS0 4 + 2 H 3 P0 4 . 

tricalcium sulfuric calcium phosphoric 

phosphate acid sulfate acid 

345. The strictly chemical use of the term " phosphoric 
acid." — The name phosphoric acid is properly applied 



MA N UFA CTUR ED PHOSPHA TES 



203 



only to the hydrated compound H 3 P0 4 , though it is com- 
monly used in agricultural literature in referring to the 
phosphorus pentoxid (P 2 5 ). 

346. The relationship of the various phosphates. — 
The relationship of the tribasic orthophosphoric acid, 
with its three hydrogen atoms replaceable by a metal, is 
shown below : — 



[OH 

PO OH 

[OH 

orthophosphoric 
acid 



fOM 

POOH 
| OH 

monometallic 
orthophosphate 



(OM 

PO OM 

[OH 

dimetallic 
orthophosphate 



(OM 
POlOM 

[OM 

trimetallic 
orthophosphate 



The union of calcium, a divalent element, with orthophos- 
phoric acid is illustrated as follows : — 



(OH 


POO/ U 


POOH 


o\ 


o\ 


Ca 


Ca 


(0/ 


(0/ 


POOH 


POOH 


(OH 


(OH 


monocalcium phos- 


dicalcium phosphate 


phate or acid phos- 


or monacid phos- 


phate of lime 


phate of lime 


CaH 4 (P0 4 ) 2 


2 CaHP0 4 



PO 



PO 



°\Ca 
Q/ Ua 

0\ 

Ca 

(0/ 

°\Ca 



tricalcium phosphate 
or neutral phos- 
phate of lime 

Ca 3 (P0 4 ) 2 



347. Care in the manufacture of superphosphate. — 
In the manufacture of superphosphate the composition 
of the raw phosphate must be determined in advance, in 
order that the right quantity of sulfuric acid of the proper 
strength may be employed. If, for example, calcium 
fluorid or calcium carbonate is present, allowance must be 
made for them so that sufficient acid will remain to react 



204 FERTILIZERS 

properly upon the phosphate. On the other hand, manu- 
facturers avoid, in so far as possible, the formation of 
free phosphoric acid, for the reason that the mass is then 
likely to be moist, to be more difficult to handle, and to be 
much more destructive to the bags used in its shipment. 

348. The practical process of making superphosphate. — 
Chamber acid, because of its cheapness, is usually em- 
ployed instead of purer grades of sulfuric acid. This 
has a specific gravity of 1.5 to 1.6. The acid and the raw 
ground phosphate are introduced into a mixer, and the 
whole mass is then passed into a "den." There the chief 
reaction follows in the course of a few hours, though the 
material is usually allowed to react for some days. During 
this time a very high temperature is developed, often 
exceeding 100° C, which is highly favorable to the decom- 
position of the remaining tricalcium phosphate. The 
gypsum produced, combines with the excess of moisture ; 
and after a short time the material dries out enough so 
that it can be readily broken up and brought into a friable 
and fit condition for use. At present, in certain works, 
the gases coming from the dens are condensed, the liquors 
concentrated in lead pipes or chambers, and the compounds 
of fluorin prepared therefrom are used in enameling por- 
celain and for other purposes. 

349. Double superphosphate. - — An unusually high grade 
of superphosphate found on the market in this country 
and in Europe is the "double " superphosphate. This is 
made by treatment of low-grade phosphates with an ex- 
cess of dilute sulfuric acid. By use of filter presses the 
gypsum and other insoluble impurities are largely separated 
from the remaining liquid mixture, which consists of sul- 
furic acid, monocalcium phosphate, and free phosphoric 
acid. This liquid is then highly concentrated, by evapora- 



MANUFACTURED PHOSPHATES 205 

tion, until it is sufficiently strong for use in treating the 
highest grades of rock phosphates, or until it is of proper 
strength to be used as a dilutant of ordinary sulfuric acid, 
employed for that purpose. The reaction of the free 
phosphoric acid of the solution upon the tricalcium phos- 
phate is represented by the following equation : — 
Ca3(P0 4 ) 2 + 4 H3PO4 = 3 CaH 4 (P0 4 ) 2 . 

tricalcium phosphoric double superphos- 

phosphate acid phate (monocalcium 

phosphate) 

By the process described above, the content of monocal- 
cium phosphate may be raised so that a product contain- 
ing from 40 to 45 per cent of soluble phosphoric acid is 
produced. It contains, however, free phosphoric acid in 
excess and is on this account difficult to dry. It may 
also prove slightly injurious for a -few days on a very 
acid soil, if used with plants which are especially sensitive 
to acidic conditions. 

It is possible by leaching ordinary superphosphate with 
water, and by evaporation of the solution, to obtain a 
material with as high as 60 per cent of soluble phosphoric 
acid. 

High-grade superphosphates are prepared in Europe as 
a by-product from the manufacture of gelatine. 

The direct manufacture of these high-grade phosphates 
is economical only where fuel is cheap and where sulfuric 
acid and low-grade phosphates are available at very low 
cost ; or where the material must be transported for long 
distances, as may yet be the case in the United States 
when the phosphate beds of Florida and Tennessee are 
exhausted and those of the far West must be drawn upon 
to supply the needs of the East. 

These high-grade phosphates are often of material 



206 FERTILIZERS 

service to the fertilizer manufacturer in the preparation 
of some of the higher grades of mixed fertilizers, for by 
their use lower grades of potassium salts or of nitrogenous 
materials may be employed than would otherwise be pos- 
sible. (See Fig. 19.) 

350. Dissolved bone. — Raw bone is now seldom 
treated with sulfuric acid, for the purpose of manufactur- 
ing dissolved bone, owing to the fact that it yields a 
sticky, gelatinous mass which it is difficult to handle. 

By steaming, bone becomes friable, and it may then be 
treated with sulfuric acid without difficulty. Owing to 
the removal of much of the fat and organic matter by this 
process, the mass dries out within a few hours after acidula- 
tion so that it can either be easily ground and utilized 
directly as a fertilizer, or it may be introduced into mix- 
tures of other fertilizer materials. 

Dissolved steamed bone necessarily varies somewhat in 
composition according to the character of the bone used 
in its manufacture. It may be safe to say that it usually 
contains from 1 to 3 per cent of nitrogen. It also contains 
from 15 to 18 per cent of phosphoric acid, the major 
portion of which is soluble in water. (See Fig. 20.) 

351. Dissolved bone-black. — The waste bone-black 
from sugar refineries, and the highly carbonized bone 
residues from annealing processes, yield, upon treatment 
with sulfuric acid, a superphosphate similar to that from 
bone, excepting for the fact that it contains little or no 
nitrogen. 

Towards the close of the preceding century acid phos- 
phate began to gradually replace dissolved bone-black, 
but still the prejudice of many farmers was so strong 
against any fertilizer made from rock that acid phos- 
phate was dyed black, in some cases, in order that it 



MANUFACTURED PHOSPHATES 



207 










o> 



-M 



1 s 



4) *S 
ej 03 

.at 






So 



208 FERTILIZERS 

might be sold for dissolved bone-black. Dyed acid phos- 
phate was also introduced into some mixed fertilizers, 
which had been compounded previously by the use of 
dissolved bone-black; but as farmers came to under- 
stand that dark or black fertilizers were not necessarily 
better than others, the tendency to resort to such meas- 
ures ceased. (See Fig. 21.) 

352. Laboratory studies on the solubility of phos- 
phates. — The recent exploitation of raw rock phosphate, 
as a fertilizer, makes a consideration of the action of cer- 
tain solvents upon the various phosphates of special inter- 
est. It must not, however, be forgotten that in the soil 
many individual factors, including living organisms, are at 
work ; and many of the chemical and physical conditions 
are also entirely different from those of the laboratory. 
Many of the phosphates studied in the laboratory are 
artificial products. They are in consequence not of the 
same physical character as certain of the phosphates 
with which the farmer has to deal. For these reasons 
great care should be taken in attempting to apply all such 
laboratory findings to the conditions practically met with 
in the field. 

With this precautionary introduction it may be well to 
consider certain laboratory observations, which may have 
a direct, or, more frequently, indirect, bearing upon the 
practical utilization of phosphates. 

353. The action of water on monocalcium phosphate. — 
As concerns the action of water upon monocalcium 
phosphate there exist widely divergent statements. 
These differences are believed to be due to the fact that 
some of the monocalcium phosphate employed by the 
different experimenters contained a little free phosphoric 
acid, which increased its solubility ; furthermore, owing 



MANUFACTURED PHOSPHATES 



209 




210 FERTILIZERS 

to the hygroscopic nature of the free acid, and to the water 
therefore absorbed, the amount of actual monocalcium 
phosphate employed may sometimes have been less than 
was supposed. 

From recent investigations it also appears that upon 
the addition of water to monocalcium phosphate a cer- 
tain amount of hydrated dicalcium phosphate (CAHPO4 
• 2 H 2 0) is formed, and at still higher temperatures even 
the anhydrous salt (CaHP0 4 ), which, unlike the hydrated 
salt, is insoluble in citric acid. At the same time the 
resulting solution contains a higher ratio of phosphoric 
acid to lime, than the monocalcium phosphate. This 
is indicated partially by the equation which follows : — 

CaH 4 (P0 4 ) 2 - H 2 + H 2 = GaHP0 4 + 2H 2 + H 3 P0 4 - 

The free phosphoric acid therefore carries with it into the 
solution some dicalcium phosphate. The addition of 
more water results in changing relatively more of the 
monocalcium phosphate into free phosphoric acid and 
dicalcium phosphate, whereas the addition of phosphoric 
acid to the solution renders more of the dicalcium phos- 
phate soluble. 

Experiments by Joly l have shown that the addition 
of monocalcium phosphate to a given amount of water 
resulted, up to certain limits, in a marked increase in the 
free phosphoric acid in solution ; but at the temperature 
at which he worked, the addition of an excess of monocal- 
cium phosphate beyond 65 grams to 100 grams of water, 
resulted in no further decomposition of the salt nor in 
further change in the composition of the solution. 

Under this last condition there are, according to Cam- 

1 Compt. rend., 97 (1883), 1480. 



MANUFACTUBED PHOSPHATES 211 

eron, two solid phases, viz. monocalcium and dicalcium 
phosphate. 

It has been shown by Cameron and Seidell l at a tem- 
perature of 25° C, that when both the monocalcium phos- 
phate and dicalcium phosphate are present as solid phases, 
the amount of " free " phosphoric acid (P 2 5 ) was 120 
grams, per liter of solution. 

354. The action of water on dicalcium phosphate. — 
When water is added to dicalcium phosphate, there is 
produced on the one hand a solution, and on the other 
an amorphous solid containing a greater ratio of lime to 
phosphoric acid than is present in the dicalcium phos- 
phate. This solid was formerly regarded as tricalcium 
phosphate. 

It has been shown by Millot and confirmed by Viard 2 
that when dicalcium phosphate is acted upon by boiling 
water, free phosphoric acid and some lime go into solution, 
whereas the solid phase is composed of amorphous tri- 
calcium phosphate and anhydrous dicalcium phosphate. 
It was supposed by certain investigators, however, that 
the solid was tricalcium phosphate and that monocalcium 
phosphate resulted, which passed into solution. Definite 
formulas have been ascribed by some investigators to the 
solid compounds resulting from treating dicalcium phos- 
phate with water, under the assumption that they were 
dealing with a distinct compound rather than with a mix- 
ture of two solid phases, or with a series of solid solutions. 
That the latter was probably the case has been shown by 
Rindell, who insured final conditions of equilibrium by 
determining at intervals the electrical conductivity of the 
solutions with which he worked. 

1 Jour. Am. Chem. Soc, 27 (1905), 1503. 

2 Compt. rend., 127 (1898), 178. 



212 FERTILIZERS 

It has been shown recently by Buch J that after subject- 
ing dicalcium phosphate to fifty-three successive teachings 
with water, it had been transformed completely into tri- 
calcium phosphate ; and he suggests the possibility of 
carrying the transformation still further, in view of the 
basic compounds of phosphoric acid which are known to 
exist in nature. 

The solubility increased by carbonic acid. — The solu- 
bility of dicalcium phosphate has been shown by Dusart 
and Pelouze 2 to be more than two and one-fourth times as 
great in water saturated with carbon dioxid as in pure 
water ; and Cameron and Seidell found that solid gypsum 
increased the solvent action of water saturated with carbon 
dioxid. 

355.. The action of water on tricalcium phosphate. — 
In connection with a study of tricalcium phosphate, it 
was found unstable when brought in direct contact with 
water, and it yielded a solution having a higher ratio of 
phosphoric acid to lime than was possessed by the original 
phosphate. At the same time a phosphate with increas- 
ing basicity is produced which, according to Cameron and 
Bell, 3 also " becomes decreasingiy soluble on repeated 
treatment with water." According to the same authorities 
the soil water, containing both mineral and organic mat- 
ter, doubtless exerts a much greater solvent action on 
the phosphoric acid of the tricalcium phosphate than is 
exerted by pure water. 

If the first work is right, it appears to offer a partial ex- 
planation of the long-continued after-effects which follow 
the application of superphosphates to soils, for by the 

*Zeits. anorg. Chem., 52 (1907), 325. 

2 Compt. rend., 66 (1868), 1327 ; cited from Cameron and Bell. 

3 Bvil. 41, Bureau of Soils, U. S. Dept. of Agr. (1907). 



MANUFACTURED PHOSPHATES 213 

reaction of the monocalcium phosphate with such basic 
phosphates as may be present therein, the basicity of the 
latter should become less, and much of the phosphoric acid 
would consequently remain, for a considerable period, much 
more readily soluble than that present at the outset in the 
original basic phosphate. 

It appears from what has preceded that what is gener- 
ally spoken of as tricalcium phosphate cannot be considered 
as a definite chemical compound, in all cases, but rather, 
in most instances, as one of a series of solid solutions of 
lime and phosphoric acid. 

The solubility increased by carbonic acid. — It has been 
shown by many experimenters that tricalcium phosphate 
is more soluble in water containing carbon dioxid than it 
is in pure water. 

A number of determinations were made by Schloesing 1 
of the solubility of a phosphate which, by analysis, was 
shown to be very close to a tricalcium phosphate. The 
results secured by treating a gram of the phosphate for a 
day at 16° to 20° C. with 1250 c.c. of solvent, were found 
to be as shown on the following page. 

The table shows the great influence of carbon dioxid on 
the solubility of such phosphate, and the low solubility of 
the phosphoric acid, in all cases, in the presence of large 
amounts of calcium carbonate. This action of calcium 
carbonate and of other calcium salts in depressing the 
solubility of tricalcium phosphate, even in the presence of 
carbon dioxid, has been suggested as being due possibly to 
the formation of a common ion (Ca) which lessens the 
quantity of phosphoric acid which passes into solution. 
On this basis potassium chloric! would be expected to have 
a solvent action upon tricalcium phosphate, and this has 

iCompt. rend., 131 (1900), 149. 



214 



FERTILIZERS 



Solvent 


P2O5 PER 

Liter. 
Milligrams 


CaO per 
Liter. 
Milli- 
grams 


Water 


0.74 

6.90 

48.50 
91.90 

0.38 

1.10 

0.80 

1.77 

1.30 




1200 c.c. distilled water and 50 e.c. water 

saturated with CO2 

1000 c.c. distilled water and 250 c.c. water 

1250 c.c. water saturated with C0 2 . . 
Water containing 174 mmg. of CaC0 3 . 

and 82 mmg. of C0 2 per liter . . . 
Water containing 290 mmg. of CaC0 3 

and 171 mmg. of C0 2 per liter . . . 
Water containing* 389 mmg. of CaC0 3 

and 270 mmg. of C0 2 per liter . . . 
Water containing 488 mmg. of CaC0 3 

and 415 mmg. of C0 2 per liter . . . 
Water containing 558 mmg. of CaC0 3 

and 541 mmg. of C0 2 per liter . . 


100 
162 
219 
273 
313 



been shown by Cameron and Hurst to be the case ; though 
they found that it also had a decomposing action, as would 
reasonably be expected. 

The solubility and decomposability increased by certain 
substances. — Sodium nitrate, sodium chlorid, and solu- 
tions of gelatine, sugar, and albumin have all been shown 
to have a solvent, and in some cases also a decomposing 
action on tricalcium phosphate. 

356. Determination of " soluble " phosphoric acid. — 
In the analysis of commercial fertilizers the first step in 
the determination of phosphoric acid is to place a weighed 
portion of the material on a filter paper, and then to leach 
it with water. By this operation practically all of the 
monocalcium phosphate (CaH 4 (P0 4 ) 2 ) is dissolved, and 
other changes in associated phosphates, as suggested 
previously, occur to a slight extent. The quantity of the 



MANUFACTURED PHOSPHATES 215 

dissolved " phosphoric acid " is determined and reported 
as " soluble " phosphoric acid (phosphorus pentoxid 
P 2 5 ). 

357. Advantages of soluble phosphoric acid. — One 
advantage of monocalcium phosphate over other phos- 
phates is due to the fact that it is readily dissolved by 
water ; and if applied as a top-dressing it is easily carried 
into the soil. If incorporated with the soil at the outset, 
it also becomes more generally distributed, as the result 
of subsequent rainfalls, than would be the case if the 
phosphate were introduced in an insoluble state. 

358. The reversion of monocalcium phosphate. — It 
is well known that the monocalcium phosphate after 
entering the soil, passes at once, or very quickly, in the 
presence of considerable moisture, into less soluble com- 
binations. Indeed solutions of monocalcium phosphate, 
if simply heated, or if allowed to stand for some time at 
ordinary temperatures, break up into dicalcium phosphate 
and phosphoric acid as follows : — 

CaH 4 (P0 4 ) 2 = CaHP0 4 + H 3 P0 4 . 

monocalcium dicalcium phosphoric 

phosphate phosphate acid 

This change takes place to some extent even in the dry- 
ing of superphosphate in the factory. This is especially 
true of superphosphate made from Florida phosphates, 
and from such other phosphates as yield a rather moist 
product. 

If the soil contains calcium carbonate, a considerable 
part of the monocalcium phosphate is supposed to react 
with it to produce essentially tricalcium phosphate, as 
follows : — 



210 FERTILIZERS 

CaH 4 (P0 4 )2 + 2 CaC0 3 = Ca 3 (P0 4 ) 2 + H 2 0. 

raonocalcium calcium tricalcium water 

phosphate carbonate phosphate 

It is supposedly for this reason, in part, that on acid 
soils the application of lime coincidently with, or prior 
to, the application of monocalcium phosphate, is desira- 
ble ; for otherwise far more of the monocalcium phos- 
phate would presumably react with iron and aluminum 
oxids and hence become subsequently less available to 
plants than the finely divided and newly formed trical- 
cium phosphate. 

359. Liming after reversion with iron and aluminum 
oxids. — In case superphosphates have been applied 
sucessively to soils rich in iron and aluminum oxids and 
poor in calcium carbonate, the proper course, if one wishes 
to render the phosphoric acid available, is to lime the land 
quite heavily ; for, as has been pointed out by Deherain in 
France, such a procedure is followed by the transformation 
of much of the unavailable phosphoric acid into calcium 
combinations which can be more readily utilized by plants. 
Similar remarkable effects of lime in rendering the phos- 
phorus compounds of the soil available to plants, or at 
least in rendering the application of phosphates no longer 
necessary, have been observed at the experiment station of 
the Rhode Island State College in connection with a soil 
which had received no phosphates for at least a dozen 
years. Similar marked benefit from liming also resulted 
on soil to which roasted aluminum phosphate (con- 
taining some iron phosphate) had been applied. Indeed, 
this benefit from liming in the latter case continued for 
several years after the last application of the lime and of 
the aluminum phosphate was made. A similar effect 
of applying lime was in some cases either entirely lacking, 



MANUFACTURED PHOSPHATES 217 

or it was far less striking, in connection with the use of 
the unroasted aluminum phosphate. 

360. The determination of " reverted " phosphoric 
acid. — After a sample of fertilizer has been leached with 
water, in the regular course of analysis, it is again extracted 
under definite conditions by digestion for one-half hour 
with a neutral solution of ammonium citrate. This treat- 
ment readily brings into solution phosphoric acid present 
as dicalcium phosphate (CaHP0 4 ), regardless of whether 
it was formed by the reversion of monocalcium phosphate 
or otherwise. 

361. " Reverted " phosphoric acid not all from dical- 
cium phosphate. — In addition to dicalcium phosphate 
there is also dissolved by this treatment about one-half 
of the phosphoric acid which is present in steamed bone 
tankage, and a considerably less proportion of that in 
steamed bone. The ammonium citrate solution also dis- 
solves to a great extent the phosphoric acid present in 
roasted iron and aluminum phosphates. 

Since the term " reverted " is applied to all of the phos- 
phoric acid removed by the extraction with ammonium 
citrate solution, it is evident that the so-called reverted 
phosphoric acid may be derived from dicalcium phosphate, 
tricalcium phosphate, and even from iron and aluminum 
phosphates. It is obvious, therefore, that its value to the 
farmer is likely to be variable, and conditioned not only 
upon its source, but in some cases even upon whether it is 
used on soils which are acid or upon those which are well 
supplied with carbonate of lime. 

362. The term "available" phosphoric acid. —Avail- 
able phosphoric acid is the term applied to the sum of 
the soluble and reverted phosphoric acid, determined 
as just described. It is therefore a trade term, rather 



218 ' FERTILIZERS 

than one always strictly indicative of its agricultural 
value. 

363. Insoluble phosphoric acid. — The phosphoric acid 
remaining undissolved after the successive extractions with 
water and ammonium citrate solution is finally deter- 
mined and designated " insoluble " phosphoric acid. If 
such phosphoric acid is present in bone and in bone tank- 
age, it will have a materially higher crop-producing value 
than if it is present in mineral tricalcium phosphate. If 
in this latter form, it will likewise be more readily available 
to plants than if present in powdered apatite or in the 
unroasted phosphates of iron and aluminum. It is ob- 
vious, therefore, that the mere analytical statement may 
fail, in certain particulars, to give complete information 
concerning the probable fertilizing value of the insoluble, 
as well as of the reverted, phosphoric acid. As concerns 
the soluble phosphoric acid, on the contrary, it is equally 
valuable, regardless of the source from which it may have 
been derived. 

364. The reversion of monocalcium phosphate. — In 
addition to the reversion of monocalcium phosphate 
to dicalcium phosphate, and finally to tricalcium phos- 
phate, when brought together with calcium carbonate, 
monocalcium phosphate may react upon tricalcium 
phosphate, in the presence of moisture, in such a way 
that, for many months after a fertilizer is mixed, the 
soluble and the insoluble phosphoric acid become grad- 
ually less and the reverted phosphoric acid increases 
correspondingly. This reaction may be expressed as 
follows : — 

Ca 3 (P0 4 ) 2 + CaH 4 (P0 4 ) 2 = 4 CaHP0 4 . 

tricalcium monocalcium dicalcium 

phosphate phosphate phosphate 



MANUFACTURED PHOSPHATES 219 

365. Reversion often beneficial in some respects. — 
Such a reaction, though beneficial from the standpoint of 
the availability of the phosphoric acid present originally in 
the insoluble tricalcium phosphate, lessens the value, at 
least for top-dressing, of the phosphoric acid present at 
the outset in the " soluble " state. Owing to the con- 
siderable amount of water involved in the formation of the 
hydrous salt which s produced (CaHP0 4 • 2 H 2 0), the rate 
of the reaction in fertilizers in storage is determined in 
part by the rate at which water can be absorbed from the 
air, although in the soil this change would be very rapid. 

366. Reversion with iron and aluminum oxids serious. 
— The most serious form of reversion which may result 
in a superphosphate in the soil, is that which takes place 
when monocalcium phosphate reacts upon iron and 
aluminum oxids or upon sulfates of these elements. The 
first of these reactions maybe suggested by the following : — ■ 

2 Fe 2 (OH) 6 + 3 CaH 4 (P0 4 ) 2 = 2 Fe 2 (P0 4 ) 2 + Ca 3 (P0 4 ) 2 4- 

ferric monocalcium ferric tricalcium 

hydrate phosphate phosphate phosphate 

12 H 2 0. 

water 

The tricalcium phosphate produced in this case can 
react upon further quantities of monocalcium phosphate 
to cause additional reversion. 

It is well understood that the presence of iron oxid, in 
excess of 2 per cent, in phosphates intended for super- 
phosphate manufacture, is objectionable, and that 
above 4 per cent is prohibitive. This is due to the fact 
that the oxid is dissolved by the sulfuric acid, and thus 
the way is paved for the more rapid subsequent reversion 
of the phosphoric acid. This is a most serious form of 
reversion because of the low availability of the iron phos- 



220 FERTILIZERS 

phate produced, especially under unfavorable soil condi- 
tions. 

The reaction just referred to is a reversible one, as 
indicated below : — 

3 FeP0 4 + 3 H 2 S0 4 ^± (FeP0 4 -2 H 3 P0 4 ) + Fe 2 (S0 4 ) 3 . 
However, in the presence of an excess of sulfuric acid, it 
proceeds as follows : — 

2 FeP0 4 + 3 H 2 S0 4 ^1 2 H 3 P0 4 + Fe 2 (S0 4 ) 3 . 
The reaction of such compounds with monocalcium phos- 
phate is shown by the following : — ■ 
Fe 2 (S0 4 ) 3 + CaH 4 (P0 4 ) 2 = 2 FeP0 4 + CaS0 4 + 2 H 2 S0 4 . 

Notwithstanding that this reaction is probably never 
complete, a great amount of insoluble ferric phosphate is 
nevertheless formed. The sulfuric acid set free might 
then unite with more iron, and thus the process could be 
repeated until equilibrium is finally established. 

Reactions are possible with aluminum compounds, 
similar to those described above for ferric oxid and for 
ferric sulfate. 

In case ferrous oxid were present, instead of the ferric 
oxid, a possible reaction has been suggested as follows : — ■ 

4 FeS0 4 + 20 + CaH 4 (P0 4 ) 2 + 3 Ca(P0 4 ) 2 

ferrous oxy- monocalcium tricalcium 

sulfate gen phosphate phosphate 

= 4 FeP0 4 + 4 CaS0 4 + 2 H 2 

ferric calcium water 

phosphate sulfate 

According to Schucht, however, who demonstrated 
the matter experimentally, the reaction takes the follow- 
ing course : CaH 4 (P0 4 ) 2 • H 2 + Fe 2 (S0 4 ) 3 + 5 H 2 = 
FeP0 4 • 2 H 2 + CaS0 4 • 2 H 2 + 2 H 2 S0 4 ; then, H 2 S0 4 
4- CaH 4 (P0 4 ) 2 • H 2 = CaS0 4 -2 H 2 4- 2 H 3 P0 4 ; and, 



MANUFACTURED PHOSPHATES 221 

finally, 2 (FeP0 4 • 2 H 2 0) + 4 H 3 P0 4 = 2 (FeP0 4 • 2 H 3 P0 4 ) 
+ 4 H 2 0. In fact, the hydrated iron phosphate may, in 
the superphosphate, become wholly insoluble again, as 
shown below : — 

FeP0 4 • 2 H 2 + CaS0 4 = CaS0 4 • 2 H 2 + FeP0 4 . 

It is for the foregoing reasons that the Redonda and 
other iron and aluminum phosphates cannot be utilized 
for superphosphate manufacture, and hence are roasted, 
or subjected to certain other chemical treatment, as a 
means of increasing their availability. 

367. Reversion as affected by pyrite. — The presence 
in phosphates of small amounts of pyrite (FeS 2 ) and of 
silicates of iron and aluminum is sometimes unobjection- 
able from the standpoint of the superphosphate manu- 
facturer, for the reason that they are usually but partly 
soluble in sulfuric acid and do not react with monocalcium 
phosphate. Nevertheless, the solvent action of these 
substances does not always hinge upon sulfuric acid only, 
for the hydrofluoric acid liberated from the calcium fluorid, 
often present in superphosphates, readily decomposes 
silicates. Under certain conditions aluminum silicate in 
considerable amounts may therefore eventually cause 
reversion of the phosphoric acid. 

368. The fixation of superphosphates in soils rapid. — 
Many experiments have been conducted with soils, em- 
bracing those which are highly calcareous, sandy, and 
clayey, also with and without admixtures of precipitated 
calcium carbonate, marl, oxids of iron and alumina, in 
order to ascertain the rapidity of the fixation of soluble 
phosphoric acid. In many of these laboratory experi- 
ments, as, for example, in one by Schroeder in which two 
parts by weight of superphosphates were used with eight 



222 ' FERTILIZERS 

parts of loam, the proportions between superphosphate 
and soil were entirely unlike those existing in the field, for 
in actual practice only from 200 to 1200 pounds of super- 
phosphate are usually applied per acre, representing a 
depth of from six to ten inches of soil. Notwithstanding, 
therefore, that in the former case only a trifle over half 
of the phosphoric acid was fixed at the end of twenty 
days, the usual application in the field might, under favor- 
able conditions of rainfall, have been fixed in a single 
day. In fact, a great preponderance of evidence supports 
the idea that very rapid fixation of soluble phosphoric 
acid takes place under the usual conditions of farm prac- 
tice, provided the rainfall is sufficient to largely dissolve 
and distribute the monocalcium phosphate; and that 
losses by leaching are small. In times of drought, how- 
ever, particles of superphosphate which have lain for a 
considerable period in the soil have been found to still 
contain soluble phosphoric acid. 

369. The fixation of phosphates confined chiefly to 
the surface soil. — Upon examining the soil of the Broad- 
balk wheat field at the Rothamsted experiment station 
in England, Dyer found that notwithstanding the fifty 
annual applications of 350 pounds per acre of high-grade 
superphosphate, the subsoil from a depth of nine inches 
downward contained practically no more phosphoric acid 
removable by a 1 per cent citric acid solution than where 
none had been applied. Nevertheless, the upper nine 
inches of soil showed that it had been enormously enriched 
by phosphoric acid which the citric acid solution was 
capable of extracting. It must be evident in this case 
that if the fixation had not been very rapid, much of the 
phosphoric acid must have been washed into and fixed 
by the subsoil. 



MANUFACTURED PHOSPHATES 223 

The analysis of the drainage waters at Rothamsted has 
shown but a trifling loss of phosphoric acid, which further 
supports the foregoing conclusion. 

370. The availability of fixed phosphates may still be 
high. — It has been found at the Rothamsted station 
that five or six successive extractions of the soil with the 
citric acid solution bring it to a state where subsequent 
extractions fail to yield materially more than was remov- 
able from the original soil phosphates. The sum of the 
amounts of phosphoric acid removed in the first five 
extractions, added to that taken out by the crops of the 
fifty years, also agrees very closely with the quantity 
added during the interval, in superphosphates. In this 
particular case the efficiency of the stored-up phosphate 
was doubtless greatly enhanced by the presence in the soil, 
during the interval, of considerable quantities of carbonate 
of lime. Under this condition less phosphoric acid prob- 
ably entered into combination with iron and alumina than 
would otherwise have been the case. See Fig. 22. 

371. Injury from applications of superphosphate rare. — 
If superphosphates are applied a short time before plant- 
ing, there is no likelihood of their causing injury to the 
crops. A striking instance of injury to oats, when ap- 
plied just before seeding, was noticed upon an unlimed acid 
soil at the experiment station of the Rhode Island State 
College, in the case of double superphosphate, although 
it was not observable with any of the other superphos- 
phates which were used. This ill effect, however, which 
was indicated by the unhealthy appearance and blanching 
of the tips of the leaves, finally disappeared within an 
interval of only a few days, probably after the initial 
acidity had been reduced, by the soil reactions, below the 
critical point for that particular plant. 



224 



FERTILIZERS 




MANUFACTURED PHOSPHATES 225 

372. Soils on which superphosphates may give poor 
results. — It has been found on the acid peat soils of 
Germany (Hochmoor) that the first application of acid 
phosphate often has little effect and that the use of dical- 
cium phosphate, bone, basic slag meal, or even of certain 
unacidulated mineral phosphates is followed by better 
results. On such soils, as well as on those which are light 
and sandy and more or less acid, the use of acid phosphate 
is not likely to be followed by the best possible results, 
unless they have first been limed. 

373. Superphosphates have a flocculating action on 
soils. — In experiments by Sachsse and Becker 1 it was 
shown that superphosphate has a greater flocculating 
effect upon clayey particles of soils than either gypsum 
or lime. It should therefore improve their tilth and their 
ability to hold and to deliver water properly to the plant. 
Superphosphate is recognized as improving, in this par- 
ticular, such soils as have been made alkaline by long use 
of nitrate of soda. 

374. Various soil conditions affecting the choice of 
phosphate to be used. — It has often been reported that 
on the highly calcareous soils of Norfolk, England, where 
fine bone meal was of little value, superphosphates were 
found to act splendidly on the turnip crop ; for they not 
only encouraged immediate and vigorous growth, but 
pushed the plants along so fast that they very largely 
escaped injury from the turnip fly. 

Acid soils of every kind are not as a rule ideally 
adapted to superphosphates unless they have first re- 
ceived applications of wood-ashes, or lime in some suit- 
able form. 

On all ordinary soils, superphosphates are especially 

1 Die landw. Vers.-Sta., 43 (1894), 22. Cited from E. S. R., 5, 696. 
Q 



226 FERTILIZERS 

effective, and, contrary to a somewhat common idea, 
the after-effects from their use are long continued. 

Notwithstanding that superphosphate acts well on 
certain highly calcareous soils, Petermann recommends 
especially for them the dicalcium phosphate, which is 
not only easily dissolved by carbonic acid, but is also 
readily drawn upon by plants, by virtue of the direct 
action of their roots upon the phosphate. 

375. Crops and conditions for which superphosphates 
are especially adapted. — Many experiments in Europe, 
supported by results in this country, show that few if 
any plants respond more quickly or more favorably to 
superphosphates than the turnip. Coming in the same 
category close behind the turnip may be mentioned the 
cabbage and the other closely related plants such as 
Brussels sprouts, kale, kohl-rabi, and cauliflower, also 
many of the quickly maturing garden crops, such as 
lettuce, beets, spinach, and radish. 

Superphosphates are especially adapted to all cases 
where spring top-dressing is practiced, as, for example, 
on grass land, for clovers, alfalfa, and winter grains. 

Certain writers for the agricultural press recommend, 
on the contrary, for such purposes basic slag meal and 
fine bone meal ; yet it not infrequently happens that the 
rainfall is light after the spring applications have been 
made ; and instances have occurred where, for several 
weeks after the fertilizer was applied, hardly more than 
one-fourth of an inch of rain has fallen. Under such 
circumstances grass crops have been increased from two 
to two and one-half tons per acre by the top-dressings, in 
which acid phosphate was used, whereas if the phosphoric 
acid had been applied in bone or in basic slag meal, it 
would have been practically without effect on the grass 



MANUFACTURED PHOSPHATES 227 

crop of that season. Indeed, the consequences which 
must follow in such cases, if phosphates insoluble in water 
are used, are too obvious to require further illustration. 

The use of liberal amounts of superphosphates, es- 
pecially in conjunction with generous applications of nitrog- 
enous and potassic fertilizers, has been found to be es- 
pecially helpful in connection with the culture of the sugar 
beet ; for by their use the maturity is hastened and the 
sugar content consequently increased. Similarly, the use 
of extra superphosphate for potatoes not only often in- 
creases the total crop, but also the percentage of starch, 
due chiefly to the hastening of maturity. The use of 
superphosphate is also helpful in some cases because by 
hastening maturity the crops may more surely escape frost. 

Recent studies have shown that superphosphates aid the 
germination of seeds to a remarkable degree, as compared 
with other fertilizer ingredients. 



CHAPTER XVII 



POTASSIC FERTILIZERS 



In earlier times wood-ashes and the ashes of sea-weeds 
were the chief sources of potash, but at present the sup- 
plies for the entire world are practically all drawn from the 
German mines. 

376. Wood-ashes and lime-kiln ashes. — Wood-ashes 
constitute one of the most ancient sources of potash, not 
only for industrial purposes, but also for use as a fertilizer. 
They may contain from 2.5 to 12 per cent or more of potash 
(potassium oxid, K 2 0), dependent upon the temperature 
of the fire, the kind of wood used, and the freedom from 
impurities. As offered for sale in the United States, at 
present, the potash content usually ranges from 3 to 8 per 
cent. In addition, they contain from 30 to 35 per cent of 
calcium oxid, 3 to 4 per cent of magnesium oxid, and from 
1 to 2.5 per cent of phosphoric acid, together with im- 
purities and other ingredients of little or no fertilizing 
value. 

Leached wood-ashes contain usually but from 0.3 to 1 
per cent of potash, the quantity depending upon the 
thoroughness of the leaching. 

Lime-kiln ashes, which consist of a mixture of waste 
lime and wood-ashes or coal-ashes, rarely contain more 
than from 1 to 2 per cent of potash. 

377. Cotton-seed hull ashes. — A prominent source of 
potash, used very extensively at an earlier date for the 
growing of tobacco in the Connecticut Valley, was the 

228 



POTASSIC FERTILIZERS 229 

ashes produced in the burning of cotton hulls, known in 
the trade as " cotton-seed hull ashes." In the analysis 
of forty samples at the Massachusetts agricultural experi- 
ment station the potash content was found to range from 
10 to 42 per cent, the average being 22.48 per cent ; they 
also contain from 3 to 13 per cent of phosphoric acid, about 
9 per cent of lime, and 10 per cent of magnesia. It is 
obvious that material ranging so widely in potash content 
should be bought only by analysis or on a definite guaranty. 

378. Saltpeter waste. — A by-product known as salt- 
peter waste has been found by the Massachusetts experi- 
ment station to range in potash content from 5.6 to 13.7 
per cent. The chlorin present amounted to 4.6 per cent, 
the sodium oxid to 37 per cent, and the nitrogen to from 
0.52 to 3.3 per cent. 

This material, like all factory by-products, can be bought 
with safety only on analysis. 

379. Other wastes containing potash. — In addition 
to the foregoing, there are a vast number of other waste 
products, including prussiates, cyanid residues, and brick- 
kiln ashes, which are used for manurial purposes; but 
they usually contain widely variable percentages of potash, 
and some of them sometimes contain objectionable sub- 
stances ; for this reason they hardly deserve further men- 
tion in this connection. 

380. Potash from sea-weeds and other plants. — 
Among the plants which serve as prominent sources of 
potash along the sea-coast, may be mentioned the marine 
algae familiarly known as " sea-weeds." Incidentally 
unusual interest has just been aroused in the recovery of 
potash from sea-weeds, chiefly on account of difficulties 
with the German potash producers, due to contracts made 
between the owners of certain individual German mines 



230 



FERTILIZERS 



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POTASSIC FERTILIZERS 



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232 FERTILIZERS 

and certain groups of American fertilizer manufacturers. 
It has, in consequence, been again proposed to make use 
of the enormous masses of sea-weeds available on the Pacific 
coast. This is no new idea, for sea-weeds have been thus 
utilized in the past, and even certain salworts (Salsola) 
have been expressly cultivated, collected, and burned in 
Spain, Sicily, and elsewhere, and the fused ashes sold 
under the trade name of " barilla." Ashes of these plants 
from near the Caspian Sea are said to contain 5 per cent 
of potash which is readily soluble in water. 

In earlier times straw and weeds of various kinds were 
used for the manufacture of both sodium and potassium 
carbonates. At various times it has been proposed to 
utilize for this purpose wormwood, tansy, the common 
marigold, and other plants rich in alkalies. 

381. Analyses of sea-weeds. — Many analyses of 
sea-weeds common on the New England coast have been 
made by Wheeler and Hart well, 1 and these, with analyses 
by others, are given in the tables on pages 230 and 231. 

382. Tobacco stems. — Tobacco stalks and the waste 
midribs from the leaves are often sold as " tobacco stems." 
The Massachusetts agricultural experiment station re- 
ports six analyses of such material showing the potash 
content to range from 3.76 to 8.82 per cent. With a 
moisture content of 10.6 per cent, the average potash per- 
centage was found to be 6.44. Such tobacco stems are also 
rich in nitrogen besides containing small quantities of 
lime and magnesia. The potash present in the dried 
stems may be very largely removed by mere extraction 
with water, and even the insoluble potash residue must, 
in the process of decomposition, become very readily 
available to plants. 

1 Bui. 21, R. I. Agr. Exp. Sta., January, 1893. 



POTASSIC FERTILIZERS 233 

383. Indian corn cobs. — It has been shown that In- 
dian corn cobs contain an average of about 6.8 per cent of 
potash and that the ashes made from them contain about 
50 per cent of potash, 1 hence the ashes of corn cobs have a 
greater total fertilizing value, per ton, than muriate of 
potash or the high-grade sulfate of potash. 

384. Potassium nitrate. — One of the oldest and best 
known sources of potash, until the discovery of the Ger- 
man potash deposits, was "niter," or potassium nitrate. 
This material usually contains from 12 to 14.5 per cent of 
nitrogen, in addition to 44.5 to 45.5 per cent of potash. 

Potassium nitrate is especially valuable for agricultural 
purposes wherever it is desirable to avoid the sulfuric 
acid and chlorin which are present in the German potash 
salts. Unfortunately, the supply is so limited, and the 
price in consequence so high, that it only occasionally 
comes into close competition with the German potash 
salts and the Chilian nitrate of soda. Nevertheless, there 
have been several years during the last two decades when 
the American farmer might have effected a decided saving 
in the purchase of his fertilizer supply had he bought 
potassium nitrate instead of the usual potash salts and 
nitrate of soda. 

A discussion of the methods used in the manufacture of 
potassium nitrate are to be found elsewhere (Section 241). 

385. Potassium carbonate. — In the Caucasus there 
exist many factories for the manufacture of potassium 
carbonate, which is sold on the basis of 90 per cent of pure 
potassium carbonate. The chief impurities are sodium 
carbonate, 5 per cent; potassium sulfate, 2 per cent; 
and potassium chlorid, 6.5 per cent. In 1906 eleven such 
factories were reported in Russia. This material, like 

1 E. S. R., 17 (1905-1906), 1054. 



234 ' FERTILIZERS 

potassium nitrate, is also to be recommended whenever 
chlorids and sulfates must be avoided ; but it is more 
applicable to soils of an acidic character than to those 
well supplied with basic ingredients. If used in large 
quantities, it has a tendency to dissolve humus and to 
bring about deflocculation of the mineral matter, and 
consequently its use on certain soils may be disadvan- 
tageous. 

386. History of the German potash deposits. — The 
German potash salts, which to-day constitute one of the 
most valuable possessions of any country of the world, 
were at the outset looked upon as a hindrance in the pro- 
duction of common salt. 

Salt works had already existed in Stassfurt, Germany, 
for a long period of time. They were at first the prop- 
erty of the Duke of Anhalt, they then passed into other 
hands, and in 1796 were sold to the Prussian " Fiscus." 
In the years from 1830 to 1840 common salt was discovered 
by borings made south of the Harz Mountains, in the 
Thuringian basin. The brines there were so favorable for 
the manufacture of salt that the weak brine at Stassfurt 
could not be used in successful competition with them, and 
hence the Stassfurt works were finally closed in 1860. 

On April 3, 1839, a boring was begun at Stassfurt, and in 
1843 at a depth of 256 meters the upper covering of the 
salts was met. It was then continued for 325 meters in 
the salt, without reaching the bottom of the deposit. The 
result of this undertaking was entirely unexpected, as 
well as a great disappointment at the outset, for instead 
of securing a saturated solution of common salt the saline 
solutions also contained large amounts of magnesium 
chlorid and potassium chlorid. It was concluded, how- 
ever, by Doctor Karsten and Professor Marchand that 



POTASSIC FERTILIZERS 235 

at greater depths common salt would be met, and in 1852 
the sinking of two shafts was begun. At the end of five 
years common salt was found at a depth of 330 meters ; 
but in reaching the deposit it was necessary to penetrate 
250 to 280 meters of potassium and other salts. 

Soon thereafter similar discoveries were made at Neu 
Stassfurt, Loderburg near Stassfurt, and at Douglashall 
near Westeregeln. In a word, boring followed boring, 
not only north of the Harz Mountains, but to the south- 
ward and elsewhere, and mine after mine was opened at 
such frequent intervals as to increase the number, soon, to 
more than 150, thereby taxing the ability of the newly or- 
ganized German potash syndicate to control the situation. 

387. Americans buy a German potash mine. — Finally 
the Virginia-Carolina Chemical Company of the United 
States purchased a German mine, and on July 1, 1910, when 
the proposed renewal of the German potash syndicate 
failed, large contracts for potash salts, continuing for sev- 
eral years, were made by certain mine owners with Ameri- 
can fertilizer manufacturers. 

388. The famous potash contracts. — The reign of high 
prices for potash salts and the end of the former great Ger- 
man monopoly seemed now to have arrived. At this junc- 
ture the Reichstag passed a measure, practically creating a 
government monopoly of the potash salts. This situation 
soon led to diplomatic exchanges on the subject between 
the United States and Germany. As a result of this and 
subsequent agitation a new syndicate was formed, and the 
American contracts have finally been otherwise adjusted 
or withdrawn. 

389. Mode of occurrence and distribution of potash 
deposits in Europe. — In the course of the search for these 
saline deposits in Germany, it has been found that they are 



236 FERTILIZERS 

not confined to any particular geological formation, for 
they occur from the Permian to the Tertiary, though the 
deposits near Stassfurt underlie the "Bunter" sandstone 
of the Triassic period. 

The following shows the arrangement of the deposits 
in the order from top to bottom in which they are more 
commonly found in the vicinity of Stassfurt : — 

Alluvial deposits. 

Diluvial deposits. 

" Bunter " (Brown) sandstone (Triassic). 

Gypsum, anhydrit, red clay, etc. 

Newer common salt (a later secondary formation, 
frequently lacking). 

Anhydrit (anhydrous calcium sulfate). 

Salzthon. 1 

Carnallit region. 

Kieserit region. " Abraum " salts. 2 

Polyhalit region. 

Older common salt. 

Anhydrit. 

Frequently kainit is found in the upper part of what is 
essentially the carnallit region, but its presence is not 
universal. 

Schonit, sylvanit, and many other minerals also occur 
in these deposits, though not usually in great quantities. 

390. The chemical composition of the more important 
potash salts is given in the following table : — 

1 The Salzthon is made up of three layers, consisting at the bottom 
of calcium sulfate, in the middle of magnesia (uncombined) and alumina, 
and at the top of clay and from 40 to 50 per cent of magnesium carbonate. 
This forms an impervious and protecting cover for the potassium and 
magnesium salts below. 

2 A term applied because these salts were over, and in the way of 
getting at, the common salt, which necessitated their removal. 



POTASSIC FERTILIZERS 



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238 FERTILIZERS 

391. Duration of the deposition of potassium salts. — 
In the common salt are to be found thin bands of anhydrit 
which have been taken to represent the records of yearly 
deposits of gypsum during the colder season of the year. 
Based upon this and other features connected with the 
deposits, it was estimated, in 1864, that they might have 
been formed in 1500 years ; but later estimates * place 
the time at from 10,000 to 13,000 years. At all events 
there seems to be no doubt that the deposition took place 
in a salt inland lake either fed by springs or having for a 
long time a continued or intermittent connection with the 
ocean. 

392. Natural deposits of potassium salts elsewhere. — 
Up to the present time no discovery of large and important 
deposits has been made aside from those in Germany and 
a few in Austria. The occasional rumors of really im- 
portant discoveries in the United States still lack confir- 
mation. The discovery of such deposits at any time need 
not, however, be a matter of surprise, for it would seem 
that elsewhere than in Europe, lying above the salt de- 
posits of like origin, the potassium and magnesium salts 
of the mother liquors may likewise have crystallized out ; 
and they may also have been similarly preserved from the 
action of water by a natural protecting cover, just as they 
are by the " Salzthon " in Germany. 

393. Kainit. — The most important of the natural 
salts, used directly as a fertilizer, is kainit (see analysis, 
p. 237), which, though it contains potassium sulfate, also 
carries large quantities of chlorids. It is used somewhat 
extensively in Europe, due in part to the low transportation 
charges. Kainit has been employed to some extent in the 

1 Die Salzindustrie von Stassfurt und Umgegend von Dr. Precht, 
Stassfurt, 1889, p. 5. 



POTASSIC FERTILIZERS 239 

United States for direct application to the soil, though its 
chief use has been in compounding " complete " commer- 
cial fertilizers. 

The employment of kainit in fertilizer mixtures is 
usually indicated by the fact that their chlorin content, 
in such cases, is usually a little more than twice as great as 
the per cent of potash. 

Because of its chlorin content, kainit is to be avoided 
in the growing of sugar beets and tobacco, and also in 
the production of potatoes, if they are intended for starch 
manufacture. This is due to the depressing effect of chlorin 
upon the starch and sugar content of certain plants, pro- 
vided that the application is made in the spring in which 
the crops are grown. In the case of tobacco the chlorin 
affects injuriously the color of the ash, and also the burn- 
ing quality. Extended experiments in Europe have dis- 
closed the fact that good crops may be secured, and that 
this ill effect may be avoided, by using extra heavy appli- 
cations of kainit in the year preceding the one in which 
these sensitive crops are to be grown, and by omitting it en- 
tirely the following spring. It has been found, in such cases, 
that no serious losses result from leaching, and the subse- 
quent efficiency of the potash is not materially endangered. 

394. Sylvanit and carnallit. — Another crude but less 
abundant salt, often applied directly to the land, is syl- 
vanit. This consists chiefly of chlorids and contains 
about 12 per cent of potash. It is sold in Europe at a 
lower price than kainit. 

Carnallit. — In Germany even the crude carnallit, 
containing about 9 per cent of potash, is also applied 
directly as a fertilizer ; but it can neither be transported 
long distances nor can it be stored with safety in moist 
places because of its hygroscopic character. 



240 FERTILIZERS 

395. Muriate of potash. — The manufactured potash 
salt exported most extensively from Germany is the 
muriate of potash. The grade chiefly employed in agri- 
culture is the one containing from 48 to 50 per cent of 
potash, equivalent to from 80 to 85 per cent of potassium 
chlorid. The remaining 15 to 20 per cent consists chiefly 
of common salt, associated with small amounts of sodium 
and magnesium salts and a little water. 

396. High-grade sulfate of potash. — The grade of 
sulfate of potash most commonly manufactured and sold 
for agricultural purposes in the United States is that con- 
taining from 47 to 48.5 per cent of potash, or about 90 
per cent of potassium sulfate. This is usually designated 
as " high grade " sulfate of potash, in order to distinguish 
it from a lower grade which contains large amounts of 
magnesia, in addition to potash. The small amounts of 
other ingredients in this potash salt are given in the pre- 
ceding table (p. 237). 

397. Double sulfate of potash and magnesia, or double 
manure salt. — Following the foregoing manufactured 
potash salts in agricultural importance, in the United 
States, is the double sulfate of potash and magnesia, also 
known as " double manure " salt, containing from 25 
to 27 per cent of potash, or approximately 50 per cent of 
potassium sulfate. The fact that this salt also contains 
34 per cent of magnesium sulfate (MgS0 4 ), and that it 
is essentially free from chlorids, makes it especially ap- 
plicable for soils which may possibly lack magnesia, and 
for situations where sulfur is possibly needed or where 
chlorin should be avoided. 

This salt should not be employed as a source of potash 
on soils already relatively too rich in magnesia. 

At the present time potash in the two sulfates costs, 



POTASSIC FERTILIZERS 241 

in the United States, about one and one-quarter cents 
per pound more than in muriate of potash. 

The double sulfate of potash and magnesia has been 
used by Goessmann and Brooks at the Massachusetts 
experiment station with especially good results, in com- 
bination with other fertilizing ingredients, in the manuring 
of apple trees. 

398. Double carbonate of potash and magnesia. — 
The double carbonate of potash and magnesia is a hydrous 
salt, also prepared in Germany, which has been used in 
several instances with excellent results in the United States. 
The material, according to an analysis made at the Massa- 
chusetts experiment station, was found to contain 18.5 
per cent of potash and 19.5 per cent of magnesia. 

In experiments at the Rhode Island experiment station 
it was found especially helpful in cases where not only 
potash but also an alkaline treatment of the soil was 
demanded; hence it is to be recommended wherever 
magnesia is not already present in too great amounts and 
where muriate of potash and sulfate of ammonia either 
fail to produce their full effect or are toxic, because of an 
acidic condition of the soil. 

399. Silicate of potash. — A silicate of potash for 
agricultural use, containing from about 24 to 27.6 per 
cent of potash, has been prepared in Germany and dis- 
tributed in this country for experimental purposes. It 
was thoroughly tested by Brooks in Massachusetts and 
found to be a valuable fertilizer, ranking in efficiency 
between the muriate and the high-grade sulfate of potash. 
It is, however, of less interest than otherwise, because its 
manufacture is said to have been discontinued. 

400. Potassium carbonate (Pearl ash). — Potassium 
carbonate (Pearl ash) and so-called " potashes," consisting 



242 ' FERTILIZERS 

of potassium carbonate and potassium hydrate, have been 
used as fertilizers to a small extent, and also in compost 
heaps. The former compound has found considerable 
application in the growing of tobacco. In experiments 
at the Rhode Island experiment station, covering a period 
of seventeen years, it has been found to give, with most 
crops, materially better results on a silt loam soil of acid 
character than an equivalent amount of potash in muriate 
of potash. Had the soil been alkaline at the outset, or 
nearly so, doubtless the reverse might have been true, as 
was found by W. P. Brooks in certain experiments in 
Massachusetts. 

401. Greensand. — A natural potash mineral of very 
low grade, but yet of some fertilizing value, which has been 
used more or less extensively as a manure, at points 
near where it occurs, is " greensand " or " greensand 
marl." 

This has generally been supposed to be a sea-bottom 
deposit, but it has recently been asserted that similar 
zeolitic compounds are probably formed by the action of 
magmatic waters. Greensand occurs widely, but the 
deposits of chief interest in the United States are found in 
New Jersey. According to Cook, the material has an 
average content of about 5 per cent of potash, and it often 
contains in addition from 1 to 2 per cent of phosphoric 
acid. The greensand is a hydrated silicate of iron and 
potassium, a species of glauconite. Its action is slow, 
as might be expected, and the effects of a single heavy 
application are visible for a dozen years. It, like the other 
zeolites, is capable of being decomposed by hydrochloric 
acid, and hence it readily parts with the lime, magnesia, 
soda, and potash which it contains. 

Much virtue is ascribed by many writers to these zeolitic 



POTASSIC FERTILIZERS 243 

compounds by reason of the fact that the bases are mu- 
tually interchangeable, and because of the prominent part 
they are supposed to play in giving to the soil its ability 
to absorb and hold lime, potash, and magnesia, when they 
are applied for manurial or amendatory purposes. 

It has been proposed by H. Wurtz x to utilize the green- 
sand as a source of potash by fusing it with calcium chlorid, 
a method employed recently by Cushman and others for 
treating potash feldspars. 

402. Phonolite, nepheline, alunite, leucite, and feld- 
spars as sources of potash. — It was suggested long ago 
by Storer 2 and others that certain feldspars (orthoclase 
feldspar, K 2 • A1 2 3 • 6 Si0 2 , if pure, contains 17 per cent 
of potash) might possibly be so finely pulverized as 
to make them valuable fertilizers. Especial interest 
was recently awakened in the subject by Cushman, 3 
who claimed to have found feldspar, thus prepared, of 
decided value in the growing of tobacco. 

It has been shown by F. Schacke, Tacke, and Popp, 4 
and by H. von Feilitzen, 5 that powdered phonolite and 
nepheline ((Na • K) 2 0(A1 2 3 • 2 Si0 2 )) were of some value 
as potash fertilizers, but were far inferior to the Ger- 
man potash salts. The results with feldspar and with 
alunite were, however, too poor to make them worthy 
of consideration as practical potassic fertilizers. The 
value of finely ground feldspar has also been carefully 
studied by Hart well and Pember. 6 They employed a 
finely ground product capable of passing a screen having 

1 Storer, Agriculture, 2 (1897), 487. 

2 Agriculture, 2, 1897. 

3 Bui. 28, Office of Public Roads, U. S. Dept. of Agr. 
4 Chem. Ztg., 35, 1222; Abs. Chem. Abstracts, 6, 1048. 
6 Deut. Landw. Presse, 38 (1911), 737, 738. 

6 Bui. 129, Agr. Exp. Sta., R. I. State College. 



244 



FERTILIZERS 



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of potash 



Fig. 24. — Treatment of Millet. 




Ground feldspar Sulfate of potash 

Fig. 25. — Treatment of Wheat. 



POTASS IC FERTILIZERS 245 

200 meshes to the linear inch, and containing about 9 per 
cent of potash, 3 per cent of soda, and less than 0.4 
per cent of lime. The work was done in pots which were 
supplied regularly with water to the optimum limit, where- 
by the conditions for bringing the potash into solution 
were far better than those usually met with in farm 
practice. 

In the course of these experiments, beans, wheat, and 
Japanese millet (Panicum crus-galli) were grown. As a 
result it was found that the feldspar possessed such slight 
value as a fertilizer that no one could think of using it to 
replace the German potash salts. 

It has been proposed that leucite (K 2 • A1 2 3 • 4 Si0 2 ), 
containing 22 per cent of potash, might be heated with 
salts of lime or soda whereby the solubility and efficiency 
of the potash for plant production would be increased. 
Although it is admitted that much is gained by such treat- 
ment, yet the product has never been placed in successful 
competition with the German potash salts. 



CHAPTER XVIII 

THE THEORY AND PRACTICE OF POTASH FERTILIZATION 

The fact that the ocean contains far more sodium salts 
than potassium salts is explained on the ground that 
sodium is far more easily removed than potassium, from 
its zeolitic and other combinations, by the natural pro- 
cesses of leaching. This is also well illustrated by the 
well-known fact that in the natural weathering of certain 
basic rocks the relative potassium content increases pro- 
gressively, whereas the relative sodium percentages be- 
come less. 

403. The alleged ill effects of the chlorin of potassium 
and other salts. — According to A. Mayer, 1 calcium and 
magnesium chlorids are not particularly injurious to 
meadow grasses. It is asserted by L. von Wagner that 
chlorids are not good for beets and potatoes, but he doubt- 
less refers to their depression of the sugar and starch con- 
tent, which can be avoided by making the applications 
the preceding year. 

It has been explained by O. Loew 2 that the ill effect 
of chlorids is probably due to the liberation of hydro- 
chloric acid in the plant cells and to the fact that, unlike 
nitric and sulfuric acids, little of it is assimilated, on 
which account the accumulation soon reaches toxic limits. 

In discussing the beneficial action of the carbonate, sul- 

1 Lehrbuch der Agrikulturchemie (1886), 295. 

2 Bui. 18, U. S. Dept. of Agr., Div. of Veg. Phys. and Path., p. 18. 

246 



POTASH FERTILIZATION 247 

fate, nitrate, silicate, and phosphate of calcium, Ullmann l 
says that calcium chloric! is injurious to plant life. 

It is stated by Griffiths, 2 based upon observations by 
Jamieson and Munro, that potassium chlorid is a plant 
poison and that investigations in England and on the con- 
tinent of Europe have shown it to be an unreliable potash 
manure. It must, however, be recognized that the danger 
was greatly overdrawn by Griffiths in view of the fact 
that enormous quantities of muriate of potash are used 
throughout the world, with unquestionably good results. 

Certain early experiments by Nobbe, 3 with buckwheat, 
have been very generally cited in the past in support of 
the alleged benefit derived by plants from chlorin, but 
A. Mayer 4 holds that Nobbe attached undue weight to the 
matter. Nevertheless, observations on potatoes by Pfeif- 
fer 5 are said to indicate that chlorin was helpful, yet 
Pagnoul found, on the contrary, that chlorin was injurious 
to the growth of potatoes when grown on a sandy (sili- 
cious) soil. It should be recalled in this connection that am- 
monium chlorid has also been used by some experimenters 
with good results, whereas others consider it a plant poison. 

404. Reasons for the diversity of ideas concerning 
chlorids. — In an attempt to throw light on the reason 
for the quite contrary views of so many leading authorities, 
Wheeler and Hartwell 6 experimented with several different 
chlorids. Calcium chlorid was highly toxic to potatoes 
on an acid soil, but either caustic magnesia or slaked lime 
was shown to be capable of correcting the condition. 

1 Kalk unci Mergel (1893), 9. 

2 A Treatise on Manures, p. 225. 
3 Landw. Vers.-Sta., 6, 118; also 13, 398. 
4 Landw. Vers.-Sta., 49, (1901). 
6 Landw. Vers.-Sta., 49, 349-385. 

6 loth An. Rpt. R. I. Agr. Expt. Sta. (1902), 289-304. 



248 ' FERTILIZERS 

Magnesium chlorid was not found to be toxic for barley 
under the same conditions, yet ammonium chlorid was 
exceedingly toxic. In the latter case the toxicity was 
wholly corrected by calcium carbonate. The same re- 
sult was also secured with caustic magnesia, after allow- 
ing ample time for it to become well carbonated in the soil. 
In other experiments in which ill effects were observed 
from the use of muriate of potash, these were completely 
overcome, and the fertilizer was made to produce normal 
results by the employment with it of basic slag meal or 
other basic substances. 

In field experiments at the Rhode Island experiment 
station, potatoes of excellent cooking quality have been 
grown annually, with few exceptions, for a period of twenty 
years with muriate of potash as the sole source of potash. 
These results followed, even though the potash salt was 
applied in the spring, immediately before planting. Slaked 
lime had, however, also been applied periodically to the 
soil, which may have been an important factor in bring- 
ing about such a result. 

From these various experiments it appears probable 
that the highly toxic effects, reported as due to chlorids, 
may often have been caused, in consequence of a lack of 
basic substances in the soil. In fact, Schultz, of Lupitz, 
demonstrated conclusively that occasional applications 
of marl were necessary on the light acid soil of his sec- 
tion of northern Germany, in order to insure good 
results from repeated applications of the German potash 
salts. 

It has been pointed out by H. Ley * that neutral salts 
prevent or check dissociation. It is possible, therefore, 
that the lessening or hindering of unfavorable dissociations, 

1 Ber. der deut. chem. Gesell., 80, 2192. 



POTASH FERTILIZATION 249 

induced in the soil by the use of chlorids, may account in 
some measure for the benefit derived from lime and other 
basic substances. 

405. The use of chlorids increases the need of liming. — 
When chlorids of potassium and other bases are used on 
soils well supplied with carbonate of lime, double decom- 
positions result whereby the chlorin unites with the lime 
and magnesia, forming the corresponding chlorids. These 
chlorids, in reasonable quantities, are not only not ob- 
servably toxic in the presence of an excess of carbonate of 
lime ; but, owing to their high solubility, they readily 
leach away in seasons of heavy and frequent rainfall. 
This is true especially if the chlorid of potassium is 
applied a few months, or preferably the autumn or spring, 
preceding the growing of such crops as are most subject to 
injury by chlorin. 

Muriate of potash is reported by many as giving 
usually slightly greater yields of potatoes than the sulfate 
of potash, though the tubers are often claimed to be of 
inferior cooking quality. In regions of heavy rainfall, 
and where plenty of lime is used, the danger in this respect 
seems to be greatly lessened or overcome. 

406. The fate of sulfate of potash in the soil. — 
Sulfates are less objectionable in the soil than the chlorids, 
for the reason that plants require and utilize considerable 
sulfur. Furthermore under temporary or long-continued 
anaerobic conditions due to heavy rainfalls, sulfates are 
readily reduced by bacterial action, with the result that 
sulfide are formed from which even so weak an acid as 
carbonic acid may disengage hydrogen disulfid, at the 
same time forming carbonates. 

When sulfate of potash is employed on soils rich in lime, 
one result of the exchange of bases is the production of 



250 • FERTILIZERS 

calcium sulfate. This salt is relatively insoluble, for 
about 400 parts of water are required to effect the solution 
of 1 part of it, whereas calcium chlorid soon liquefies upon 
exposure to the air. 

On this account, especially if the conditions are 
occasionally favorable to reduction, the soil may not 
become so rapidly depleted of its supply of lime when 
using sulfate of potash as when muriate of potash is used. 

407. Concerning the retention of potash by soils. — 
It was already known in the time of Aristotle that common 
salt is partly removed from solution upon leaching it 
through sand or soil. It was also shown by Way, in 1850, 
that when sulfate and muriate of potash are applied to 
ordinary soils, the sulfuric acid and chlorin appear in the 
drainage waters combined with lime and magnesia, and 
that the potash is held quite completely and tenaciously 
in the soil in zeolitic (zeolites are combinations of alumina, 
silica, water, and the bases lime, magnesia, soda, or potash, 
or various combinations of these bases) and other mineral 
and organic chemical combinations. 

It is now maintained by physicists and physical chem- 
ists that the phenomenon of absorption may embrace three 
distinct processes : (1) a mechanical inclusion called 
imbibition, illustrated by the absorption of water by a 
sponge or by soil ; (2) the partial taking up of the dissolved 
substance to form a new compound or a solid solution l 
such as is claimed to result in the absorption of phosphoric 
acid, by lime, or by ferric oxid ; (3) absorption which is 



1 A solid solution is a crystalline, amorphous, homogeneous solid 
capable of changing its composition with the changing concentrations 
of the liquid solution in contact with it. A definite compound, on the 
other hand, is "stable in contact with a liquid solution of its constituents 
over a measurable range of concentration." 



POTASH FERTILIZATION 251 

the concentration or condensation of the substance in 
solution on the surface of the absorbing medium. 

It has been held by Cameron that potash is probably 
held in soils by absorption. 

Notwithstanding that in laboratory experiments, in 
which relatively small amounts of soil are usually em- 
ployed, the removal of potassium from weak solutions 
of potassium sulfate and of muriate of potash is never 
complete ; yet the conditions are entirely unlike those in 
field operations, in which the amount of material is most 
minute in its relation to the great volume of soil. It may, 
nevertheless, be true that on sandy soils, which are greatly 
deficient in clay, silt, and vegetable matter, potash salts may, 
in extreme cases, be subject to moderate losses by leaching, 
and they should consequently be used with some caution. 

408. The teachings of the Rothamsted investigations. — 
In the drainage waters from the unmanured experi- 
mental plots of the Broadbalk wheat field at Rothamsted, 
Voelcker found 1.7 parts of potash per million, whereas 
in the drainage waters from the other plats receiving as 
much as 300 pounds of sulfate of potash per annum, he 
found only 2.9, 3.3, and 4.5 parts per million. An ex- 
amination of the same soils by Dyer showed that about 
half of the potash applied, in excess of that removed by 
the crops, during a fifty-year period, was still present in 
the upper nine inches of soil, and much of it was still soluble 
in a 1 per cent solution of citric acid. Still further por- 
tions of the excess of potash were found in the second and 
third nine inches, which were also found to be soluble in 
the citric acid solution. 

409. Various factors affecting absorption. — Absorption 
appears to be dependent upon at least the following 
factors : — 



252 



FERTILIZERS 



(1) The solubility of the given substance in the solvent 
employed, although the relation is as yet unknown. 

(2) The character of the absorbing substance, though it 




Full ration of 
sodium carbonate 



Full ration of potassium 
carbonate 



Fig. 26. — Treatment of Spinach. 
Both lots limed and fertilized alike with nitrogen and phosphoric acid. 



is uncertain in how far this is determined by the area of 
exposed surface and by the character of the surface in- 
volved. 



POTASH FERTILIZATION 253 

(3) In a given solvent the rate of absorption of different 
substances in solution is variable, even with one and the 
same absorbing medium. This is so marked in some cases 
that partial separations of two different salts in the same 
solution may be thus made. 

(4) Selective absorption from electrolytes, as when 
potassium chlorid is filtered through soil, cotton, or other 
absorbents. In this case the filtrate not only becomes 
less concentrated, but even contains free hydrochloric acid. 

(5) The rate of absorption increases with the concen- 
tration of the solution and with the amount of the absorb- 
ent or of its effective surface. 

410. Potassium essential to plant growth. — It is fully 
accepted that potassium is absolutely essential to plant 
growth, even notwithstanding that it may, for many kinds 
of plants, be partially replaced by sodium, in connection 
with one or more of its possible functions. The degree, 
however, of even this partial replacement appears to be 
largely dependent upon the particular kind of plant 
involved. 

411. Potassium aids carbohydrate formation. — It 
has been found that the curtailment of the potassium 
supply exerts a serious effect upon the formation of car- 
bohydrates, such as starch, sugar, and cellulose; and in 
actual field practice certain crops especially rich in starch 
and sugar seem to require its liberal employment. 

412. Other functions of potassium. — It is now also 
held that potassium performs valuable functions in the 
formation of the proteins, and that it aids cell and nuclear 
division. It has also been asserted by Loew that potas- 
sium acts as a condensing agent, which would facilitate 
the building up of carbohydrates from formaldehyde, as 
Loew has previously suggested. 



254 FERTILIZERS 

413. Potassium increases the size of the individual 
grains of cereals. — In experiments by Hellriegel and 
Wilfarth it was found that, with the supply of phosphoric 
acid or of nitrogen curtailed, the quantity of grain was 
greatly lessened; but yet the weights of the individual 
kernels were but slightly, or not at all, affected. When, 
however, the supply of potash was curtailed, the size of 
the individual grains became smaller, and the formation 
and translocation of starch was soon interfered with or 
prevented. 

In the later years of the barley experiments at the 
Rothamsted experiment station, after a lack of potash 
became evident, it was found that the average weight of 
the grain per bushel for a period of fourteen years was 
greater where potassium salts were used in the fertilizer, 
and the average weight per kernel was increased thereby 
in an even far greater degree. 

414. Effect of potassium on photosynthesis. — Other 
experiments at Rothamsted with mangel wurzels show 
that with the leaf production varying but little, the addi- 
tion of potassium salts to the other fertilizers increased 
the yield of roots nearly two and one-half times. When 
these roots were analyzed, it was found that the increase 
in weight was due almost wholly to the increased produc- 
tion of sugar and of other carbohydrates. It would 
appear, therefore, that the process of photosynthesis in 
the leaf and the consequent possibility of the storage in 
the roots of the products elaborated by the leaves, is 
largely regulated by the potash supply available to the 
plant. In this instance the crop of roots was increased, as 
a result of the use of the potassium salts, from 12 to 29 
tons and the total product of sugar from 0.797 ton to 
2.223 tons. 



POTASH FERTILIZATION 255 

415. Potassium in connection with turgor. — Notwith- 
standing that many writers even yet refer to " the func- 
tion " of potassium salts as if potassium performed only 
the function which has just been discussed, it appears 
probable that there may be several. It has even been 
asserted by Copeland l that potassium is both a direct 
and indirect factor in maintaining the turgor of the plant. 
The importance of this conclusion may, however, be 
doubted in view of the work of De Vries, 2 who, though 
upholding for a time the importance of certain organic 
acids in maintaining turgor, concluded later that growth 
may occur without turgor and that rapid growth may 
lessen it. It is also asserted by Pfeffer that turgor can- 
not furnish the energy essential to growth, but that on 
the contrary it is a result of the conditions of growth. 

416. The functions of potassium not necessarily shown 
by the result which its absence produces. — As concerns 
the association of potassium solely with the function of 
aiding in the formation and translocation of starch, 
Pfeffer 3 is of the opinion that phosphorus may be as 
necessary in that respect as potassium, and he affirms 
" that the function of an essential element is by no means 
directly indicated by the result which its absence pro- 
duces." 

417. Potassium as a neutralizer and carrier within the 
plant. — It has been pointed out by Shimper 4 that or- 
ganic acids are the normal product within the plant of the 
synthesis of the proteins. In experiments by Mercadente 5 

1 Bot. Gazette, 24 (1897), 411. 

2 Bot. Ztg. (1879), 848. 

3 The Physiology of Plants, translated by Ewart (1900), I, 141. 

4 Zur Frage der Assimilation der Mineralsalze durch die griine 
Pflanze. 

6 Abs. Jahresb. Agr. Chcniie (1885), 257. 



256 ' FERTILIZERS 

in which he grew certain species of Oxalis and of Rumex 
without potassium, it was found that only one-eighth of 
the normal amount of acid was produced, and that the 
oxalic and tartaric acids formed were in combination with 
lime. In this case, only small amounts of starch and sugar 
were present in the sap of the plants. It is known that 
the neutral and more especially the acid salts of potassium 
and oxalic acid which are normally formed in these plants, 
are toxic to them if they accumulate in undue quantities. 
Nevertheless, it has been suggested by Wheeler and Hart- 
well that potassium perhaps performs a valuable office in 
the plant by forming soluble combinations with some of 
these acid synthetical by-products, in which state they 
may be readily transported to other parts of the plant, 
where by their combination with lime they are transformed 
into comparatively insoluble and non-toxic compounds, 
and are eliminated from the circulation. In this case 
potassium would not only act as a neutralizer, but also as 
a convenient and even necessary transporting medium. 

418. Potassium may contribute to the " luxury con- 
sumption " of plants. — It has been shown by careful 
investigation in Germany that a certain minimum of 
lime, magnesia, potash, and soda is essential to plant 
growth, but that plants require, nevertheless, a certain 
excess of bases above these total minima which may be 
supplied indiscriminately by any one or more of them ; 
for this reason, if there is a lack of the other bases, potas- 
sium may be helpful by virtue merely of supplying this 
so-called (though necessary) " luxury " consumption. 

419. Certain functions and effects of potassium salts 
in soils. — In some cases potassium salts may perform a 
useful function in the soil by virtue of increasing the sur- 
face tension of the soil solution, by which the rate of the 



POTASH FERTILIZATION 257 

capillary movement of water toward the surface and to- 
ward the plant roots is increased. 1 It is also asserted by 
King (I.e.) that the presence of salts in the soil lessens 
evaporation from the surface, so long as they remain in 
solution, and if they crystallize out they serve in a measure 
as a mulch. 

Attention has recently been called by Muntz and 
Gaudechon 2 to benefit which they allege may result in 
certain cases from the addition to soil of soluble fertilizer 
salts, since they lower the vapor pressure of the water 
and induce a distillation, to the affected points, of water 
vapor from the soil below and from the air above. 

If soils are too open, the use of the German potash salts 
may gradually improve their physical condition, by vir- 
tue of the fact that they react with calcium carbonate, if 
present, to form potassium carbonate, which salt has a 
highly deflocculating action. If, on the contrary, a soil is 
exceedingly fine, like many clay soils, the potassium car- 
bonate may by the same action injure the existing con- 
ditions, rendering the soils too compact and consequently 
difficult to till. It may make them at the same time also 
less suited in other respects to support plant growth to 
the best advantage. In these particulars the varying 
effects are analogous to those resulting from the residual 
soda of nitrate of soda (Section 254). 

420. The effect of potassium salts on legumes. — The 
beneficial effect of potassium salts upon clover and other 
legumes has long been generally recognized, and many 
soils which have been found to be deficient in potash have 
come to be termed " clover sick." It is nevertheless 
true that clover sickness may sometimes be due to a lack 

1 King, Text-book of the Physics of Agriculture (1901), p. 106. 
2 Compt. rend., 48 (1909), 253-258. 
S 



258 ' FERTILIZERS 

of lime, to disease, or other conditions ; and one is not 
necessarily justified in assuming which of the various 
causes of the failure of clover may need to be dealt with, 
without special knowledge of the particular locality and 
of the soil concerned. 

In view of the known promotion of the fixation of at- 
mospheric nitrogen by certain plants, including the leg- 
umes, when the associated bacteria are well supplied with 
carbohydrates, it appears that at least one way in which 
potassium salts may be helpful to the legumes is by in- 
creasing the carbohydrate supply within the plant, by 
which the organisms of the root nodules are made to work 
more effectively. 

In the permanent grass experiment at the Rothamsted 
experiment station, the herbage in 1902, where a mineral 
fertilizer containing phosphates, sulfate of potash, mag- 
nesium salts, and sodium salts had been used in the past, 
was 55.3 per cent legumes ; whereas where potassium salts 
were omitted from the fertilizer mixture, the legumes 
amounted to but 22.1 per cent; and where nitrogen was 
applied and the potassium salts were omitted, no legumes 
were to be found. 

421. The effect of a lack of potassium on grasses and 
other plants. — On the plots of land at Rothamsted where 
potash was most deficient, the grasses very largely failed 
to produce seed and the stalks were weak and brittle. 
This was assumed to be due to an insufficient devel- 
opment of carbohydrates within the plants. It is further 
mentioned by Hall that the grass possessed an abnormal 
color, lacked chlorophyl, and exhibited other signs of 
malnutrition. The leaves of Swedish turnips developed 
under similar conditions a " flecked " appearance, mangel 
wurzels were attacked by a leaf-spot fungus (Uromyces 



POTASH FERTILIZATION 259 

beta), wheat developed much rust, even when little was 
present elsewhere, and grass was attacked by various 
fungi. 

Whether the ill effects arising from a deficiency of potash 
were due to a lack of general vigor or to an altered com- 
position of the plant cells, Hall does not attempt to con- 
clude, although he inclines to the former view. Concern- 
ing these results, Hall cautions against giving too much 
weight to such effects, in general farm practice, since the 
manurial conditions were most unusual and had been 
developed during the long term of years in which the ex- 
periments had been in progress. i 

422. Potassium salts act best in wet seasons. — The 
effect of potassium salts upon wheat and barley, at Roth- 
amsted, has been found to be far more favorable in wet 
than in dry seasons, due possibly to its preventing pre- 
mature ripening. The yield of barley in a dry season was 
18.1 bushels per acre without the use of potassium salts, 
whereas it was 30.8 bushels when they were employed. In 
a wet season the yield in the first instance was 34.9 bushels, 
and in the latter instance 41.4 bushels, per acre. It has 
been found, in the case of root crops, that potash hastens 
maturity; however, in barley and wheat the migration 
processes are quite different from those involved in the 
storage which takes place in root crops. 

423. A lack of potassium more serious for some crops 
than for others. — In the course of experiments which 
have been in progress at the experiment station of the 
Rhode Island State College since 1894, it has been found, 
where potassium salts were omitted from the otherwise 
complete fertilizer and sodium salts substituted for 
them, that clover and timothy (Phleum pratense L.) 
largely, and in some cases completely, disappeared. Nev- 



260 FERTILIZERS 

ertheless, moderate crops of redtop (Agrostis vulgaris 
With.) were still produced, although the plants gave evi- 
dence of probable faulty seed development. Where the 
potassium salts were omitted, dark spots appeared on 
the leaves of potatoes, and even a blackening of the entire 
leaf surface often resulted. This did not appear like, nor 
was it recognizable microscopically as being identical 
with, either the early or late blight of potatoes. The 
plants, as would be inferred, died prematurely. 

Notwithstanding that the conditions in this experiment 
and in those at Rothamsted were quite unusual, it may 
nevertheless be true that under conditions which exist 
in farm practice instances sometimes occur where plant 
diseases may become unusually severe, due to a lack of 
potash or of a sufficient supply of other plant food in- 
gredients, to insure normal plant development. 

424. Potash conservation in the soil by sodium salts. — 
It has been shown by Wilfarth and his co-workers at 
Bernburg, Germany ; also at Rothamsted ; and by Wheeler 
and Hart well in Rhode Island, that certain plants, when 
supplied liberally with sodium salts, take up materially 
greater quantities of it, and less of potash, than when no 
sodium salts are applied. In fact, in the case of the Rhode 
Island experiments, the conclusion seemed obvious that 
plants supplied with the necessary minimum of potash 
could, perhaps with equal advantage, use some soda to 
replace a part or all of the excess of potash which they 
might have removed from the soil, had it been present. It 
appears, therefore, that nitrate of soda and the sodium com- 
pounds associated with the German potash salts may con- 
serve, somewhat, the potash stores of the soil by prevent- 
ing a " luxury," or unnecessary, consumption of potash 
by the plant. 



CHAPTER XIX 

LIME AND ITS RELATION TO SOILS AND FERTILIZERS 

Lime has been shown not only to be a corrective, in 
the presence of an excess of magnesia or of certain other 
substances, but also to be absolutely essential to plant 
growth, and incapable of complete replacement by other 
plant food ingredients. 

425. The occurrence of lime. — Lime is present in 
combination with carbonic dioxid and also with alumina 
and silica in many of the representative rocks of the earth's 
crust. It may be present in soils in the form of minute 
crystals of apatite, or in other combinations of lime with 
phosphoric acid; likewise in gypsum (calcium sulfate), 
calcium carbonate, in zeolitic compounds, and as a con- 
stituent part of decaying vegetable matter. 

426. Distribution and effect of limestone. — Carbonate 
of lime is widely distributed in the form of rock, and 
in many respects it is the most important form of lime 
found in soils. 

Notwithstanding the wide distribution of limestone 
rocks over most of the globe, there are nevertheless soils 
upon which it appears probable that lime is sometimes 
even needed as plant food, though perhaps in such cases 
only in connection with restricted classes of plants. Gen- 
erally, however, if 1 me is required at all, it is as a soil 
amendment, either in a neutralizing or flocculating capac- 
ity. As a neutralizer it exerts a powerful influence upon 

261 



262 FERTILIZERS 

the character of the microscopic soil flora, thus vitally- 
affecting ammonification, nitrification, denitrification, and 
nitrogen assimilation. 

Lime also affects the development of certain diseases, 
not only on the roots, but also on the aerial portions of 
plants. 

It is because of these many functions of lime in the soil 
and of the many cases of contradictory effects, dependent 
upon the character of the soil, upon the kind of plant 
grown, and upon the particular plant disease involved, 




Fig. 27. 
Clover, where before liming it could not be grown successfully. It was 
said to winter-kill, which was really seldom the case. 

that the problems connected with the use of lime are of 
a very complex character. 

427. Kinds of lime used in agriculture. — " Burned " 
lime, " rock " lime, " stone " lime, and " builder's "4ime 
are various names given to the final product after the car- 
bon dioxid of limestone or marble has been expelled by 
heat. In this process 100 pounds of pure limestone (cal- 
cium carbonate) lose about 44 pounds of carbon dioxid 
and yield about 56 pounds of calcium oxid (CaO, or lime). 
Most limestone is so impure that the product, after burn- 
ing, usually contains not more than from 95 to 98 per cent 



LIME AND ITS RELATION TO SOILS 



263 



of lime ; and certain highly magnesian limestones yield, 
upon burning, a product containing about 60 per cent of 
lime and about 40 per cent of magnesia. 

Dolomite is the most highly magnesian of limestones, 
and it contains before burning 30.4 per cent of lime and 
21.7 per cent of magnesia. 

Magnesian limestones are common, yielding a burned 




Unlimed Limed 

Sulfate of ammonia 



Unlimed Limed 

Nitrate of soda 



Fig. 28. — Treatment of Silene orientalis. 

All fertilized alike with potash and phosphoric acid. A like amount of 

nitrogen was used in each case. 

product containing amounts of magnesia ranging from the 
merest traces to about 40 per cent. 

Burned limestone is often ground, without slaking, and 
sold, without further treatment, for direct application to 
the land. In other cases the lime is slacked by the addi- 
tion of about one-third its weight of water, when there 
results a fine, dry product known as " water-slaked," or 
more commonly as " hydrated " lime (Ca(OH) 2 ). This is 
proportionately poorer in lime than before slaking, on 



264 



FERTILIZERS 



account of the addition of the hydroxyl groups (OH). 
Frequently lime is slaked by mere exposure to the 
air, whereby it takes on water and carbon dioxid, form- 
ing a mixture of calcium carbonate and calcium hydrate. 
Upon long and complete exposure to the air, under the 
most favorable conditions, hydrated lime and air-slaked 
lime become practically reconverted into calcium car- 
bonate. 

Other sources of carbonate of lime for agriculture pur- 




Unlimed Limed 

Sulfate of ammonia 



Unlimed Limed 

Nitrate of soda 



Fig. 29. — Carnations. 
All fertilized alike with potash and phosphoric acid. A like amount of 
nitrogen was used in each case. 



poses are wood-ashes, the waste from the manufacture of 
acetone, soda, and from other industrial processes. 

The chief materials used for furnishing carbonate of 
lime are, however, ground shell marl, ground oyster 
shells, and ground limestone or marble. These are named 
in their order of availability. Ground limestone and 
marble are the least efficient, chiefly on account of their 
crystalline structure. 

428. The effect of lime on nitrogen availability. — It 



LIME AND ITS RELATION TO SOILS 265 

often happens in soils which are deficient in carbonate of 
lime that the application of burned, air-slaked, or hydrated 
lime, ground limestone, or marl has an almost immediate 
beneficial influence upon ammonification and nitrification. 
Cases are on record where the efficiency of certain forms 
of organic nitrogen, in soils, has been increased from two 
to a dozen times, solely as the result of a single heavy 
application of lime. 

429. The effect of lime on denitrification. — The effect of 
lime on compact clay or silt soils is to cause several small 
particles to draw together by the process known as " floccu- 
lation." As a result, the air more readily enters the soil, 
whereby the conditions are usually rendered less favorable 
for the destruction of nitrates, since denitrification is 
essentially a reducing or anaerobic process. In fact, 
Koch and Pettit 1 have shown that in soils with 25 per 
cent or less of water the denitrifying organisms lie quies- 
cent, but when the moisture content is increased, destruc- 
tion of nitrates begins suddenly ; and considerable nitro- 
gen is then liberated in the gaseous state It appears 
probable that the critical percentage of moisture would 
be found to vary somewhat with the physical character 
of the soil. 

430. The effect of lime on soil texture. — As suggested in 
the preceding paragraph, liming greatly improves compact 
silt and clay soils, especially if they are in such condition 
that they tend to bake badly. This improvement is not 
only due to hindering denitrification, but also in conse- 
quence of the general effect of a more free circulation of 
air, the creation of conditions more favorable to nitrifica- 
tion, and finally, also, by virtue of increasing the penetra- 

iCentralb. f. Bakt., II Abt., 26 (1910), 335-345, Abs. E. S. R., 23 
(1911), 123. 



266 FERTILIZERS 

bilityof the soil by water, whereby surf ace erosion is greatly 
lessened. The storage of water in the soil is also increased, 
and its subsequent capillary movement is better regulated 
and adapted to properly supplying the needs of the plants. 
Such soils, after being suitably limed, are fit to work much 
earlier in the spring than those from which lime has been 
omitted. 

It is also true of light sandy and gravelly soils that the 
use of lime often improves their condition by the mere 
adding of fine material, which increases their lifting ca- 
pacity for water. Furthermore, it is claimed that by the 
chemical combination of the lime with silica and alumina 
to form zeolitic compounds, the condition of the soil is 
not only rendered better from a physical standpoint, but 
also as concerns its ability to hold potash and other plant 
food elements. 

The physical character of light soils is also said to be 
affected favorably by the adherence of lime to the surface 
of the existing soil particles. 

In all cases heavy liming is to be avoided on light soils, 
especially in hot climates, and particularly if they are 
greatly deficient in vegetable matter. In no case should 
opportunity be lost to increase the supply of the latter, 
even though lime is used with great care and in small 
quantities. 

431. The use of lime in connection with phosphates. — 
The presence of calcium carbonate in soils may be expected 
to insure that when superphosphates of any kind are 
applied to them, some of the monocalcium phosphate will 
revert with lime rather than entirely or chiefly with oxids 
of iron and aluminum, as might otherwise be the case. 
This is quite commonly of distinct advantage in view of 
the fact that the phosphates of iron and aluminum, when 



LIME AND ITS RELATION TO SOILS 267 

once formed, are considered as being less available sources 
of phosphoric acid for plants, at least on acid soils, than 
tricalcium phosphate. They are also less soluble than the 
latter in weak acids, including even carbonic acid. 

Large applications of burned or slaked lime, or even of 
carbonate of lime, are said to be frequently important 
factors in liberating phosphoric acid already locked up in 
the soil in combination with iron and aluminum oxids, 
as has been pointed out by Deherain. 1 

The beneficial effect of applications of slaked lime upon 
the subsequent efficiency of roasted iron and aluminum 
phosphate, even for several years after the last applica- 
tion of each, has been most strikingly demonstrated at 
the agricultural experiment station of the Rhode Island 
State College. 2 This benefit is usually assumed to be due 
to the long-continued reactions resulting from the gradual 
transformation of the calcium carbonate into the more 
active bicarbonate, which then reacts more effectively 
than the carbonate upon the iron and aluminum phos- 
phates. It is possible likewise that other more complex 
factors are also involved. 

432. Lime as a destroyer of worms and slugs. — Much 
has been written of the effect of lime in destroying worms 
and slugs, and Storer 3 states that if but 3 to 4 tons of lime 
are applied per acre, some insects may escape destruction, 
but that it may be expected to be very effectual if from 
7 to 8 tons of lime are applied per acre. It must be rec- 
ognized, however, that on sandy or other light soils one 
should seldom, if ever, use more than from 1000 to 2500 
pounds of burned or slaked lime per acre, in a single ap- 

1 Traite de Chemie Agricole (1892), 525. 
2 Buls. Nos. 114 and 118. 
3 Agriculture, 2 (1897), 545. 



268 FERTILIZERS 

plication. It is but rarely that more than from 1 to 2.5 
tons per acre would be required, on heavier soils, in order 
to accomplish such changes as are immediately desirable. 
For this reason it is believed that the practical significance 
of liming, as a remedy for slugs and worms under 
usual economic agricultural conditions, has been unduly 
emphasized. 

It has been suggested by English writers that freshly 
slaked lime or, preferably, burned lime should be scattered 
in clover fields or in stubble where insect pests are common. 
This should be done, however, at or after dusk, or before 
sunrise, since the effectiveness of the lime depends upon 
its coming into direct contact with the worms or slugs, 
which appear to be unable to withstand its caustic action. 

433. Need of liming suggested by soil acidity. — Soils 
are commonly referred to as acid which quickly and 
intensely redden a blue litmus paper when brought in 
contact with it under suitable conditions of moisture. 
Unless such soils are very light and sandy, or are typical 
subsoils, they usually yield immediately, without previous 
extraction with hydrochloric acid, dark chocolate, brown, 
or black extracts, upon stirring them with water and 
dilute ammonium hydroxid. 

It has been pointed out by Cameron and others of the 
Bureau of Soils of the United States Department of Agri- 
culture, that finely divided or porous substances which can 
in no way be considered as acid, as, for example, cotton, 
have, nevertheless, the property of absorbing the base 
away from • blue litmus paper, whereupon it gradually 
takes on the color of the acid or red litmus. It should be 
remarked, however, that this reaction between litmus 
paper and cotton takes place very slowly. On account of 
these and similar observations and because some soils 



LIME AND ITS RELATION TO SOILS 



269 



which impart a red 
color to litmus pa- 
per have not shown 
subsequent benefit 
from liming (conclu- 
sions drawn some- 
times without suffi- 
cient attention to 
the requirement of 
the particular 
plant), the relia- 
bility and value of 
the litmus paper 
test for ascertain- 
ing if soils are in 
need of liming, has 
been seriously ques- 
tioned from several 
sides. It has been 
shown, x however, 
that, notwithstand- 
ing this physical 
absorptive property 
of soils, such redden- 
ing of blue litmus 
paper does not re- 
sult in the presence 
of moisture and of 
calcium bicarbon- 
ate. Again, if a con- 
siderable amount of 

1 Bui. 139, Agr. Expt. 
Sta., R.I. State College. 




270 FERTILIZERS 

active calcium carbonate is present in a soil, the rain 
water, and the soil solution charged with more or . less 
carbonic acid derived from the air, and from decomposing 
plant residues in the soil, must inevitably react with it to 
form calcium bicarbonate, the quantity of which would 
increase within certain limits with the quantity of carbonic 
acid present. For this reason the rapid and intense red- 
dening of blue litmus paper by a moistened soil, whatever 
the reaction may be ascribed to, is an indication of a suffi- 
cient lack of basic substances to possibly interfere with 
suitable bacterial development and with the growth of 
certain higher varieties of plants, unless lime or other 
basic substances are employed. 

434. Liming the most economic basic treatment. — 
Whether, therefore, a soil is strictly acid or is sufficiently 
lacking in bases to require their addition, even if for other 
reasons than for the neutralizing of acidity, liming is 
suggested as a suitable remedy. In fact, no other basic 
treatment, excepting possibly in some cases with magnesia, 
is either so economical, so lasting, or is it followed by such 
general good results, as liming. 

435. Chemical methods for determining the lime re- 
quirements of soils. — Many methods have been pro- 
posed from time to time for determining the lime require- 
ments of soils, as, for example, (1) the adding of lime-water 
to the soil, evaporating, and determining the lime remain- 
ing uncombined, and (2) the bringing of soil in contact with 
calcium carbonate and the measurement of the carbon 
dioxid evolved either at the usual or higher temperatures. 
In the latter case the period of treatment must be very 
brief, on account of the progressive destruction of organic 
matter and the consequent liberation of carbon dioxid 
from it, which is in no way related to the reaction sought. 



LIME AND ITS RELATION TO SOILS 271 

Soils are sometimes extracted with water, and the 
watery extract is titrated by use of a suitable indicator, 
taking cognizance of the probable presence of free carbonic 
acid in the extract. 

The foregoing are but a few of the methods proposed 
for the quantitative measurement of the lime require- 
ment of soils, but all fall short of perfection for practical 
purposes for the reason that they may give the total of 
basic absorption and chemical combination, or they may 
give only a fraction of this requirement. The true end 
point of the reaction in some cases is difficult to determine, 
and, furthermore, the amount of lime actually demanded 
to give the best results can only be approximated for 
certain selected groups of plants, and even the individual 
members of a group may vary among themselves in this 
respect. It is also true that amounts of lime far less than 
are shown by some of these quantitative tests are actually 
preferable, for certain crops, to the full amounts in- 
dicated. 

It is nevertheless true that certain of these methods, 
in the hands of one having a practical knowledge of the 
differences in plant requirements, when applied to un- 
known soils in conjunction with tests of soils the require- 
ments of which have been previously determined, may have 
very great value. On the other hand, however, they may 
lead to very erroneous and faulty conclusions as to the 
treatment, if placed in the hands of one having solely a 
knowledge of the chemical and laboratory side of the 
problem. 

436. The effect of lime on vegetable decay. — It is 
mentioned by Storer that lime performs valuable func- 
tions in the soil by coagulating organic matter. 

If burned or slaked lime is mixed with relatively fresh 



272 FERTILIZERS 

vegetable matter, the first effect is to retard decomposition, 
but if decay has already progressed to a considerable ex- 
tent, its introduction, in reasonable amounts, is likely to 
hasten decomposition almost from the outset. In fact, 
the action of lime in compost heaps is generally so well 
understood as to require no more than passing mention. 
Lime is also highly important in hastening ammoni- 
fication and the subsequent formation of nitrates from 
vegetable matter ; because, in order that nitrification may 
be active and progressive, there must be present some base 




Unlimed Limed Unlimed Limed 

Sulfate of ammonia Nitrate of soda 

Fig. 31. — Cranberries under Varied Treatment. 

All fertilized alike with potash and phosphoric acid. A like amount 

of nitrogen was used in each case. The cranberry is shown to thrive 

best on soil so acid as to be destructive to mangels. 

such as lime, magnesia, potash, or soda to combine with 
the nitric acid as it is formed, for otherwise the accumula- 
tion of acid soon inhibits the activity of the nitrifying 
organisms. 

437. ' The effect of lime on nitrogen content of humus. 
— ; It must be remembered that in the early stages of the 
destruction of vegetable matter, the losses of carbon and 
hydrogen are relatively great, due to their ready transfor- 
mation under usual soil conditions into water and carbonic 
acid. Thus the organic residue becomes for a time, on 



LIME AND ITS RELATION TO SOILS 273 

the percentage basis, continually richer in nitrogen. In 
this connection it should be stated that it has been shown, 
on a soil greatly in need of liming which was kept for many 
years chiefly in hoed crops, that liming lessened to a con- 
siderable extent the total humus removable by extraction 
with ammonium hydroxid ("matiere noire " of Grandeau), 
but that the percentage of nitrogen in the humus was dis- 
tinctly greater than before, thus showing the same general 
action of lime on material already well humified, in an 
acid soil, as on vegetable matter in a less advanced stage 
of humification. This tendency of the nitrogen percent- 
age to rise, after liming, is of interest in connection with 
observations by Hilgard and others to the effect that the 
higher the percentage of nitrogen in the humus, the greater 
becomes the availability of its nitrogen to plants. This 
helps also to explain the high fertility of soils well supplied 
with calcium carbonate which have become heavily 
charged with decaying plant residues. 

438. Rational rotation and the turning under of sward 
should accompany liming. — The ideal condition is reached 
when a grass, clover, alfalfa, or other sod, plenty of 
barn-yard manure, straw, or green crops are introduced 
into the soil with sufficient frequency to maintain a suit- 
able supply of vegetable matter with which to insure 
proper tilth. This material also furnishes food to the 
organisms which assimilate atmospheric nitrogen and at 
the same time, through the action of lime, yields carbonic 
acid to act upon the mineral constituents of the soil 
These residues also furnish to the plant considerable sup- 
plies of available nitrogen as ammonia and soluble organic 
matter, but primarily as nitrates. 

439. Avoidance of liming to conserve humus not wise. 
— The idea that organic matter should be kept from de- 



274 FERTILIZERS 

struction in the soil as long as possible, and that liming 
should be avoided because it hastens such destruction, is 
wholly exploded by the recent investigations of the mi- 
croscopic soil organisms and of their several beneficent 
functions ; nevertheless, liming should not be overdone. 

Sufficient lime in its burned, hydrated, or air-slaked 
condition, or as calcium carbonate, should be applied, to 




Unlimed Limed Unlimed Limed 

Sulfate of ammonia Nitrate of soda 

Fig. 32. — Asparagus differently Treated. 

All fertilized alike with potash and phosphoric acid. A like amount 

of nitrogen was used in each case. It should be noted that a fourth 

bundle is lacking at the left. This was because every plant died on 

the plot which received sulfate of ammonia but no lime. 



bring about a reasonably rapid humificationof the vegetable 
matter, but at the same time care must be taken that 
this latter supply is reasonably maintained. In this con- 
nection it should be stated that it is universally understood 
that the repeated employment of slaked or burned lime 
in unduly large quantities without stable manure, green 
manures, the turning under of sward, and without proper 
fertilization must be avoided, or dire consequences are 



LIME AND ITS RELATION TO SOILS 275 

likely to follow. This is not only true as concerns the 
exhaustion of available potash and phosphoric acid, but 
also because of the serious destruction of the vegetable 
matter already in its various stages of decomposition. 
Nevertheless, the frequent sweeping condemnation of the 
use of slaked or burned lime without regard to the cost 
of transportation and other conditions affecting its use 
is equally to be avoided. On account of their ready 
availability, such forms of lime should usually be applied 
at intervals of from four to seven years, and, if employed 
on suitable soils, in reasonable quantities, and at the right 
point in such rotations as involve the periodic turning 
under of a good grass sod, no fear of material injury to 
the land need be entertained. 

440. Carbonate of lime versus slaked or burned lime. — 
At the present time in the United States certain experi- 
ments conducted at the agricultural experiment station 
of the Pennsylvania State College are being extensively 
cited in the agricultural press, and elsewhere, as a basis 
for the unqualified denunciation of the use of burned and 
slaked lime. 

Conditions of the Pennsylvania experiment. — In the 
foregoing experiment, however, neither fertilizer nor 
stable manure was used. Slaked lime was applied at 
the rate of two tons per acre every four years, immediately 
before Indian corn in a rotation of Indian corn, oats, wheat, 
and clover. In comparison with it, like amounts of cal- 
cium oxid were used in ground limestone. In the former 
case the liming should preferably have preceded the 
seeding to wheat and clover, and the order of the rotation 
should have been reversed to give an opportunity for a 
favorable trial of the slaked lime. In the case of the lime- 
stone the application was divided into two equal parts, each 



276 FERTILIZERS 

being applied in alternate years, thus giving it a distinct 
advantage. As a result of the excessive quantity used, 
and of the application of the slaked lime at the wrong 
point in the rotation, it actually depressed many of the 
yields of Indian corn. 

The quantity of lime applied in the Pennsylvania ex- 
periment in twenty years on the basis of the four applica- 
tions, assuming a content of 70 per cent of calcium oxid, 
was 11.200 pounds of actual calcium oxid per acre. The 
soil was furthermore not greatly in need of liming, as has 




No lime Ground limestone Hydrated lime 

Fig. 33. — Alfalfa with Treatment under Farm Conditions. 
All fertilized alike with potash and phosphoric acid. Quantities of 
lime having the same total neutralizing value were used in each case. 

since been shown by Brown, and as indicated also by 
the fact that no great injury arose from several repeated 
applications of ammonium sulfate on other plots. It 
appears, therefore, that slaked lime was not only applied 
at an unfavorable time, but also in excessive quantities. 

Slaked lime highly beneficial in the Rhode Island ex- 
periments. — In striking contrast to the foregoing results, 
slaked lime has been used most successfully during a 
period of twenty years in several crop rotations at the 
agricultural experiment station of the Rhode Island 
State College, on land so greatly in need of lime at the out- 



LIME AND ITS RELATION TO SOILS 277 

set that beets, spinach, and lettuce could not be grown 
successfully without it or other alkaline fertilizers or ma- 
nures. This soil was, furthermore, so greatly in need of lime 
that a single small application of sulfate of ammonia 
became immediately toxic. It is interesting to note, 
however, that even under these extreme conditions the 
total quantity of calcium oxid employed (including any 
magnesium oxid present) was equivalent to less than 
3200 pounds of calcium oxid, per acre, in an interval of 
nineteen years. Even though in most of the instances in 
the Rhode Island -experiments, fertilizers were applied 
exclusively, the crop yields, as a rule, have been well main- 
tained, and in general less fertilizer has been used in the 
later than in the earlier years. 

The preceding experience shows, therefore, that too 
much alarm should not be occasioned by the results of 
experiments which have been conducted under unnatural 
conditions, and with unreasonably large quantities of 
slaked or burned lime. 

Slaked lime becomes quickly carbonated. — It must further 
be borne in mind that recent investigations have shown 
that slaked and burned lime, if applied in reasonable 
amounts, change quickly in the soil into the form of cal- 
cium carbonate ; hence it is essentially, as concerns subse- 
quent effect, as if it had been applied as such at the outset. 
In the course of earlier experiments made by Heiden, he 
concluded that in some cases lime remained in a caustic 
state in the soil for years; it appears, however, that he 
assumed that all lime found soluble in water and capable 
of producing an alkaline reaction was necessarily present in 
the soil as calcium hydrate. The falsity of this assumption 
is evident in view of the fact that calcium carbonate, if 
placed even in distilled water, is somewhat soluble and will 



278 



FERTILIZERS 




cause it to give an alkaline 
reaction. Furthermore, car- 
bonic acid, which is always 
present in the rainfall and 
in the soil water, increases 
decidedly the alkaline reac- 
tion, by virtue of forming 
calcium bicarbonate. Again, 
salts of lime formed by other 
weak acids may themselves 
give an alkaline reaction in 
water. This experiment by 
Heiden has been widely cited 
by various writers as a rea- 
son why hydrated or burned 
lime should not be applied 
to soils, yet had they taken 
the pains to investigate the 
circumstances, it would have 
been found that the con- 
clusion of Heiden was not 
justified by the experimen- 
tal method which was fol- 
lowed. 

The - bearing of the 
Maryland station experi- 
ments. — ■ Still another ex- 
periment, made at the 
Maryland agricultural ex- 
periment station, has been 
generally cited in the 
United States as showing 
great superiority of calcium 



LIME AND ITS RELATION TO SOILS 279 

carbonate over slaked or burned lime. In this case the 
soil was admittedly deficient in both available potash and 
phosphoric acid, and it was only in certain of the eleven 
years covered by the experiment that any fertilizer was 
applied, although its need was indicated by the small size 
of the crops which were harvested. In this case marl 
and ground oyster shells were compared with stone lime 
and burned oyster shells, as well as with burned magnesia. 
It appears, however, upon an investigation of the circum- 
stances that the total quantity of marl probably contained 
from 400 to 450 pounds of potash and approximately 
48 pounds of phosphoric acid, and that these substances 
may readily have become limiting factors in connection 
with the yields. In fact, it seems probable, in the light of 
this circumstance, that enough available potash and phos- 
phoric acid may have been secured by the crops from the 
marl, in many or all of the cases, to have accounted for 
the greater yields which it often produced. As concerns 
ground oyster shells, they often contain nearly .5 per cent 
of nitrogen and over .1 per cent of phosphoric acid, which 
may have given them some advantage over the burned 
lime. 

The fine matter associated with the marl used in the 
Maryland experiments may have improved the physical 
character of the soil. It is especially significant, likewise, 
that in some cases the burned magnesia and burned oyster 
shells actually gave larger crops than at least the ground 
oyster shells. It appears probable, also, that the Maryland 
plots were not, in all cases, sufficiently uniform in char- 
acter to justify some of the conclusions which have been 
drawn by others from the experiment. In view of this fact, 
and of the other circumstances mentioned, undue weight 
has apparently been attached to these results as a basis 



280 FEETILIZERS 

for discrimination against slaked or burned lime. In 
fact, Director Patterson, who made the experiment, still 
recommends slaked lime for many agricultural purposes. 

Views of certain eminent European authorities. — In 
conclusion it should be said that such eminent European 
authorities as Deherain in France, and Orth in Germany, 
though fully familiar with the dangers which may arise 
from the unintelligent and inordinate use of burned or 
slaked lime, nevertheless, recognize the great agricultural 
value of these forms of lime in specific cases, when used in 




No lime Lime as top-dressing in Lime harrowed in 

spring after seeding before seeding 

Fig. 35. — Timothy. All Seeded the Same Autumn. 

The lime in both cases was from the same lot, and was weighed out at the 

same time. 

reasonable amounts, and under ordinary conditions of 
culture. 

441. The penetration of lime into soils. — One of the 
usual recommendations regarding lime is to harrow it 
into the surface of the soil, for the reason that it tends to 
work downward. There can be no doubt but that the 
various forms of lime will be carried downward to a con- 
siderable extent both by mechanical washing and in solu- 
tion as bicarbonate and otherwise, especially in soils 
which are sandy and open, and which are relatively de- 
ficient in vegetable matter. 



LIME AND ITS RELATION TO SOILS 281 

On upland soils which are very compact, like certain 
silts and clays or fine soils containing large quantities of 
vegetable matter in advanced stages of decomposition, the 
chance for the descent of lime to the lower levels, excepting 
as it leaches through as nitrate, is very small, unless ex- 
cessive amounts are used. This has been well illustrated 
by the experience of Coville, who attempted to introduce 
lime-water into the lower levels of a soil rich in vegetable 
matter, only to find that all of the lime was held in a com- 
paratively thin layer of the surface soil. 

Another striking example of lime being retained in the 
surface soil is afforded in connection with the renovation 
of some of the acid peat (hoch-moor) soils of northern Ger- 
many. After liming, and other suitable treatment, these 
soils bore good crops for a few years, only to be followed 
later by frequent serious failures. Subsequent investiga- 
tion showed that this failure was due to the fact that the 
upper layer of soil had become so thin, as a result of the 
decompositions induced by the lime and by the system of 
drainage, that the crops suffered from drought by virtue 
of the fact that their roots did not penetrate to a sufficient 
depth to avail themselves of the permanent water supply. 
In fact, the lime had been of little or no value as a soil 
amendment below the level to which it was originally in- 
troduced, and the unlimed acid peat beneath was such an 
inhospitable medium that the plant roots would not pene - 
trate it to any practical extent. The unfortunate condition 
was corrected by subsoiling with a plow carrying knife at- 
tachments in the rear, and lime in a hopper on the beam, 
by which means lime was incorporated with the lower 
levels of the soil, after which the conditions for plant 
growth were again found to be favorable. 

The fact that plant roots will not readily penetrate an 



282 FERTILIZERS 

inhospitable medium has been recently demonstrated by- 
Reed in connection with some ingeniously devised experi- 
ments conducted in the laboratory of the Bureau of Soils 
of the United States Department of Agriculture. 

442. The expulsion of ammonia from soils as a result 
of liming. — Experiments by Boussingault and others 
are often cited to show that so long as lime remains in the 
soil, in a caustic state, the formation of ammonia pro- 
gresses. Observations are also on record showing that 




Limed Unlimed Limed Unlimed 

Nitrate of soda Sulfate of ammonia 

Fig. 36. — Alfalfa under Treatment. 

All fertilized alike with potash and phosphoric acid. A like amount of 

nitrogen used in each case. 

actual losses of ammonia from limed soils have been noted 
in laboratory experiments ; and likewise in fields, after 
heavy liming. In most pot experiments, however, the 
proportion of lime to soil will be found to have been far 
greater than those existing in practical field operations; 
and even the applications of lime in the field were usually 
excessive and beyond what would be employed in rational 
agricultural practice. At all events, on all ordinary clay, 
silt, or loam soils the absorptive and chemical combining 
power of the soil for ammonia is so great that no material 
losses need be feared, wherever only reasonable applica- 



LIME AND ITS RELATION TO SOILS 283 

tions of slaked or burned lime are made. This has been 
fully established at the experiment station of the Rhode 
Island State College, by both pot and field experiments, 
in connection with which applications of from 1 to 4 tons, 
per acre, of slaked lime have been made. 

It has been observed, on unlimed soil, where sulfate of 
ammonia has been used, that ammonium salts, consisting 
chiefly of the carbonate or bicarbonate, sometimes appear 
on the surface as an efflorescence, some time after the 
sulfate of ammonia is applied ; and in case the former salt 
were formed, losses of ammonia would be expected to 
occur. Where lime was employed, and the conditions for 
nitrification were better, no such efflorescence has ever 
been noticed. It therefore appears probable that there 
are cases where the retention by the soil of the nitrogen 
applied as ammonia, may be actually furthered by the 
employment of lime. 

What has preceded illustrates the danger of generalizing 
from laboratory experiments, in which quite unusual 
conditions often prevail, or from field experiments in 
which excessive applications of lime have been used, as to 
what will transpire under the usual and normal conditions 
of farm practice. Nevertheless, such data serve as a 
constant and useful warning to those who must deal with 
very open, sandy soils, to the effect that there may be 
danger of serious direct loss of ammonia if either slaked 
or burned lime is used on them in excessive amounts. 

443. The influence of lime on nitrification. — The 
influence of lime in promoting nitrification is now too well 
understood to require more than mere mention. It, or 
some other base, is essential to combine with the nitric 
acid as produced, and hence to prevent the uncombined 
nitric acid from accumulating to such an extent as to 



284 FERTILIZERS 

inhibit the further action of the nitrifying organisms. 
For this purpose slaked lime, burned lime, or carbonate 
of lime may be used ; although if either slaked or burned 
lime is employed, care should be taken not to use excessive 
quantities, for large amounts of slaked or caustic lime 
may check nitrification for a time. Such an apparent 
delay of the process of nitrification, for about ten days, 
resulted in one instance from the use of four tons of slaked 
lime, per acre, at the agricultural experiment station of 
the Rhode Island State College, on a good silt loam soil. 




Unlimed Limed Unlimed Limed 

Sulfate of ammonia Nitrate of soda 

Fig. 37. — Chicory ttnder different Treatments. 

All fertilized alike with potash and phosphoric acid. A like amount of 

nitrogen was used in each case. 



It was noted, however, that no such delay followed the use 
of one ton of slaked lime per acre. At the end of the ten 
days the plants, in the first case, practically all recovered 
their normal appearance and made vigorous growth within 
forty-eight hours after the first sure signs of improve- 
ment were noticed. This improvement was doubtless 
coincident with the time when, by natural carbonation 
in the soil, the alkalinity of the lime had been reduced 
below the point where it could check the development 
of the nitrifying organisms. This experience suggests 
the experiments by earlier English investigators who 



LIME AND ITS RELATION TO SOILS 285 

found that nitrification would not progress in undiluted 
urine until the alkalinity was lessened by the addition of 
calcium sulfate. This reacted with the ammonium car- 
bonate to form the essentially neutral salts, ammonium 
sulfate and calcium carbonate. 

It was found by Kellerman and Robinson that the ad- 
dition of calcium carbonate to a sandy loam soil was 
favorable to nitrification up to a limit of 2 per cent, or 
to a far greater limit than would ever be applied to agri- 
cultural soils. The application of magnesium carbonate, 
however, in excess of 0.25 per cent positively inhibited 
the action of the nitrifying organisms. 

444. Effect of calcium and magnesium carbonates on 
ammonification. — Experiments by Lipman 1 have shown 
that, when mixed with soil, calcium carbonate depressed 
the formation of ammonia from cotton-seed meal, but 
stimulated it in the case of dried blood ; whereas with 
magnesium carbonate the result was exactly the opposite. 
This may have been due to the difference in the relative 
calcium and magnesium content of the blood and of the 
cotton-seed meal, whereby the relation of the two was made 
favorable in one instance, and unfavorable in the other, 
to the vegetative growth of the ammonifying organisms ; 
as noted by Loew not only for certain lower organisms, 
but also for the higher agricultural plants. It has been 
suggested by Lipman that this difference in the action of 
the two carbonates upon organic matter of different 
kinds may explain the reason why the effect of magnesian 
lime is good on some soils and poor on others ; also why 
where the magnesian lime fails, the purer lime is often help- 
ful. Such practical differences in the action of the two 
carbonates as arise in farm practice may, however, not 

1 Centralb. f. Bakt., II Abt., 30 (1911), 173, 174. 



286 FERTILIZERS 

only be due to the indirect effects suggested by Lipman 
and others, whereby more or less nitrogen is rendered 
available to the plants, but it may also be due to a direct 
physiological effect upon the agricultural plants themselves, 
which, according to Loew and his various co-workers, is 
often a very important factor in plant growth. 

Recent investigations by Gile in Porto Rico appear to 
show that much wider lime-magnesia ratios may exist, 
without causing injury to certain plants, than the conclu- 
sions of Loew and his fellow-workers would indicate. 

445. General ideas as to the indirect manurial action 
of lime. — Lime has long been looked upon, whether ap- 
plied as hydrated, air-slaked, or fully carbonated lime, 
as a liberator of potash in the soil. This has been sup- 
posed to be due chiefly to mass action, whereby it may 
replace other bases in the zeolites and other similar com- 
pound silicates. Lime has also been shown by Morse and 
Curry l to increase the amount of potash freed, even from 
feldspathic and other potash-bearing minerals. 

446. Results with sodium and magnesium salts il- 
lustrate how lime acts indirectly. — An excellent illus- 
tration of a very similar liberating effect of magnesium 
and sodium is furnished by the experiments at the Roth- 
amsted station in England in connection with the wheat 
crop. These results are given by Hall from 1852 to 1901 
inclusive. Sodium sulfate, potassium sulfate, and mag- 
nesium sulfate were added singly to separate plots of land ; 
to one plot all three were added, and a fifth plot was in- 
cluded from which all were omitted. In the course of the 
first ten years potassium sulfate gave smaller yields than 
any of the other sulfates, but where all were omitted the 
yields were markedly inferior. As time progressed the 

1 Bui. 142 (December, 1909), N. H. Agr. Expt. Sta. 



LIME AND ITS RELATION TO SOILS 287 

yields secured with sodium sulfate and with magnesium 
sulfate became relatively less, and the result with potas- 
sium sulfate in the subsequent decades of the experiment 
approached somewhat closely those secured with the 
combination of all three sulfates. Bearing in mind the 
recent work of Hart and Peterson, 1 it might be thought 
that these sulfates had been helpful by virtue of supplying 
additional sulfur to the plants, rather than as a result of 
their having liberated potash. If, however, such need of 
sulfur had existed, it would have been expected that where 
it was applied the percentage in the ash of the crop would 
have been increased, which was not the case. It must, 
however, be recognized that this is not always the case 
with nitrogen and perhaps not with other of the necessary 
elements. In all cases, nevertheless, the potash percentage 
in the ash of the crop was materially increased. The 
per cent in the ash in the case where no sulfates were 
added was 9.91 ; the respective percentages found upon 
the addition of sodium sulfate and of magnesium sulfate 
were 14.68 and 14.87 ; whereas, as a result of the use of 
potassium sulfate alone the potash in the ash rose to 23.28 
per cent. With all three sulfates it amounted to 25.89 
per cent. These changes were not accompanied by in- 
creases in the percentages of either soda or magnesia. 

447. Fixation of potash after liberation by lime. — 
Notwithstanding that, in agreement with others, lime 
was found by Morse and Curry to have a marked solvent 
action upon the potash of feldspars, yet in the presence of 
considerable clay the potash was not found to have been 
rendered soluble in water. This was probably due to its 
having been fixed by the zeolitic compounds of the clay as 
fast as it was freed from the feldspar. This possibility is 

1 Research Bui. 14 (April, 1911), Wis. Agr. Expt. Sta. 



288 FERTILIZERS 

illustrated by experiments performed by Gerlach in which 
he found tricalcium phosphate more or less soluble in cer- 
tain weak acids, yet in the presence of iron and aluminum 
hydroxids no phosphoric acid was found in solution even 
after long-continued action. It was ascertained, however, 
in this case, that the phosphoric acid had been transferred 
to the iron and aluminum oxids, which fixed it as fast as 
the acid released it from its combination with lime. It 
appears probable, therefore, that as a result of the inter- 
action of the lime and feldspar, in the presence of the 




Limed Unlimed Limed Unlimed 

Nitrate of soda Sulfate of ammonia 

Fig. 38. — Chimson Clover under Treatment. 

All fertilized alike with potash and phosphoric acid. A like amount of 

nitrogen was used in each case. 

clay, the potash of the feldspar may have passed to some 
extent into zeolitic combinations, as a result of which its 
subsequent availability to plants may have become greater 
than in its original combination. It is possible also that 
in the presence of the clay considerable lime was also 
absorbed or fixed by zeolites directly, whereby the action 
of the lime on the feldspar was greatly weakened. Indeed, 
Storer states that after submitting clay to the action of 
lime-water for a week or two, it will be found that an 
appreciable quantity of the clay which was previously 
insoluble in hydrochloric acid will then be dissolved, with 



LIME AND ITS RELATION TO SOILS 289 

separation of gelatinous silica. In other words, by the 
addition of the lime to the clay, the formation of zeolites 
or compounds of similar character is apparently promoted. 

448. Caustic lime attacks powdered quartz. — It has 
been shown by Stoeckhardt that caustic lime attacks 
not only precipitated silica, but also even powdered quartz 
previously extracted with acid, forming as a result hy- 
drated calcium silicate. 

The addition of carbonate of lime to soils often increases 
their power to hold potash, ammonia, and other bases, 
either by chemical or physical means, or perhaps by both. 
Furthermore, these bases may be set free again by the 
action of the sesquicarbonate or bicarbonate of lime 
which are continually being formed in soils stocked with 
active (the term " active" is used to designate such calcium 
carbonate as is not surrounded by particles of clay or 
other matter to such a degree as to be readily protected 
from attack by carbonic acid) carbonate of lime. 

449. Losses of lime by leaching. — There are contin- 
ual losses of lime from the soil due to various causes : — 

(1) Carbonate of lime is even somewhat soluble in pure 
water, and certain salts in the soil solution are likely to 
increase the solvent action, as, for example, sodium chlorid, 
sodium sulfate, and certain ammonium salts. 

(2) The presence of carbonic acid carried to the soil in 
the rainfall, formed by absorption of carbon dioxid from 
the air, and produced by the decomposition of vegetable 
and animal matter in the soil, insures the gradual forma- 
tion of calcium sesquicarbonate and of calcium bicarbon- 
ate which may pass in some cases to a certain extent into 
the drainage water. The solubility of calcium carbonate 
has been shown to increase, at least within certain limits, 
with the amount of carbonic acid in the solution. 



290 FERTILIZERS 

(3) In the nitrification of manures, fertilizers, and of 
plant or animal residues in the soil, considerable calcium 
nitrate is formed which, not being held readily by the 
soil, is likely to be lost in the drainage unless the nitric 
acid therein is taken up by growing crops. At most 
seasons of the year and under favorable soil and cultural 
conditions, excepting in the case of a long-continued and 
excessive rainfall, there is but little loss by this means. 

(4) A considerable depletion of lime results in soils from 
the use of sulfate of potash, or sulfate of magnesia, but 
more especially from application of potassium, sodium, 
and magnesium chlorids, since the resulting calcium 
chlorid is far more soluble than calcium sulfate. Further- 
more, in case the soil is well stocked with vegetable matter 
and it becomes so wet as to temporarily exclude the air, 
calcium sulfate may be reduced to calcium sulfid, which 
in contact with carbonic acid may be decomposed into 
hydrogen disulfid and calcium carbonate, whereby some 
carbonate of lime is regenerated in the soil. 

(5) Other salts of lime are also somewhat soluble and 
may in consequence add to the losses by drainage. 

It is on account of these and other tendencies to loss 
of lime by natural drainage, and on account of the trans- 
formation of the calcium carbonate into other chemical 
combinations in the soil, that care must be taken to insure 
in soils at all times a small supply of " active " carbonate 
of lime. 

450. Coarsely ground limestone compared with fine 
limestone and marl. — It is on account of the continual 
loss of lime from the soil by drainage that most of the soils 
of the humid regions which are formed from conglomer- 
ates, granite, gneiss, certain shales, schists, and sand- 
stones, are usually deficient in lime. For the same reason 



LIME AND ITS RELATION TO SOILS 291 

soils of limestone regions lying even but a few feet above 
marl, chalk, or limestone beds often become sufficiently 
exhausted of their carbonate of lime to require its supply 
to the surface soil. 

It must be obvious from what has been said that the 
coarser the particles of lime added to the soil, the longer 
some of them will remain as calcium carbonate, or, in 
other words, the longer some effect of a given application 




No lime Ground magnesian limestone Ground limestone 

Fig. 39. — Alfalfa Tbeatment on Farm. 

All fertilized alike with potash and phosphoric acid. Quantities of 
lime having the same total neutralizing value were used in each case. 
On certain other soils in the same State, ground magnesian limestone 
was found to be superior to the ordinary ground limestone. 

will endure. It is, however, false philosophy to assume 
that the lime which endures longest in the soil is neces- 
sarily either the most efficient or the most economical. 
It is, nevertheless, possible that there is a limit of fineness 
which permits of the preparation of ground limestone in 
a single grinding operation, a high percentage of which 
will pass a sieve with from 30 to 60 meshes to the linear 
inch, at such low cost that it is better economy to use 
more of the coarser material than a smaller quantity 
ground to a greater degree of fineness. If, in each case, 



292 FERTILIZERS 

the same amount of material, passing a 30 or 50 mesh 
screen, can be secured at the same price, the still coarser 
associated material will cost nothing, and hence the pur- 
chaser might do better, if the transportation charges were 
low, to buy the coarser product. 

In other cases it may be better to use less of a fine, 
readily available, and efficient product, and to repeat the 
application at more frequent intervals, than to buy, for 
a larger sum of money, coarser material which, even though 
some of it will remain in the soil longer, will nevertheless 
tie up a large cash investment for a longer period of time. 
No definite rule can therefore be applied to these cases, 
since the fineness and character of the product, the rate 
of interest, the character of the soil, the freight charges, 
the cost of hauling by team, and other factors must de- 
termine the choice of the purchaser in individual cases. 

451. Concerning the practical use of lime. — Burned 
lime, finely ground or crushed, may be used at rates rang- 
ing from a quarter of a ton on certain light soils to two 
and one-half tons on extremely acid soils which are rich 
in humus, capable of immediate extraction with ammo- 
nium hydroxid. A third more, in weight, of air-slaked or 
hydrated lime may be used under the same circumstances, 
or somewhat more than double the quantity of ground 
limestone or marl. 

Care should be taken to learn from small experimental 
plots about what quantities of lime are necessary, on a 
given soil, to insure success with the special crops to be 
grown ; and this amount will often be found to be far short 
of the total " lime requirement," as indicated by certain 
quantitative laboratory methods. 

Excessive liming is something to be especially avoided, 
for the natural tendency of farmers is to carry it to ex- 



LIME AND ITS RELATION TO SOILS 293 

tremes as soon as the advantages from the use of lime have 
once been fully recognized. 

On rocky pastures which cannot be plowed, lime must 
obviously be applied to the surface ; and for this purpose 
ground limestone, or, preferably, shell marl or wood-ashes, 
are much to be preferred to burned or slaked lime. 

On mossy lands, in bad general condition, small appli- 
cations of some form of lime may be made to advantage 
just before plowing; but the chief part of the application 
should be made afterward, when it should be immediately 



4» «•* m w 



Limed Unlimed Limed Unlimed 

Nitrate of soda Sulfate of ammonia 

Fig. 40. — Watermelons variously Treated. 

All fertilized alike with potash and phosphoric acid. A like amount of 

nitrogen was used in each case. 



and thoroughly harrowed into the soil. In all such cases 
the principle should be borne in mind that the nearer a 
particle of lime can be brought to each particle ' of soil, 
the better will be the result. 

For most purposes, in ordinary farm practice the har- 
rowing of the lime into the soil after plowing is to be rec- 
ommended, though on land which cannot be plowed, car- 
bonate of lime may be spread broadcast on the sod in 
order to bring in clover and certain nutritious grasses 
which may otherwise fail to thrive. 

452. Pure lime compared with magnesian lime. — 
Instances are on record, as in the experiments by Pat- 



294 ' FERTILIZERS 

terson, 1 in which burned magnesia in certain instances has 
given better results than burned lime, and there are, for 
example, certain soils, as in parts of New Jersey and else- 
where, upon which magnesian lime gives generally better 
results than pure lime. The reverse is also true in still 
other localities in New Jersey and elsewhere in other states. 
This is usually due to the presence in the soil of relatively 
much greater quantities of magnesia than of lime, and in 
such cases the use of highly magnesian lime may some- 
times become objectionable. 

Within a few years new and important light has been 
shed on the whole question by Loew and his various co- 
workers, which will be discussed in full in considering 
magnesia. 

As a general rule it is at least erring on the safe side if 
one avoids liming repeatedly with a highly magnesian 
lime, and uses, alternately, a purer grade of lime. 

!Bul. 110, Md. Agr. Expt. Sta. (1906), 13-21. 



CHAPTER XX 

LIMING IN ITS RELATION TO PLANTS 

The subject of liming is just as important in its rela- 
tion to plants as in its relation to soils and fertilizers, and 
in this respect the complexity of the whole question be- 
comes increasingly great with each new research which is 
conducted. 

453. Plants may transform lime compounds. — The 
function of plants in aiding in the transformation of 
one lime compound into another suggests itself by the 
fact that lime is taken up abundantly by common sorrel 
from soils in which carbonate of lime is practically absent. 
When once within the plant, the lime performs the valuable 
function of neutralizing and removing from the circula- 
tion, as insoluble calcium oxalate, some of the oxalic acid, 
the excessive accumulation of which is toxic even to the 
plant in which it is produced. This compound in its 
turn, like calcium acetate and other organic calcium salts, 
is readily broken up into calcium carbonate in the soil in 
the course of the normal processes of decay ; thus actually 
tending in a slight degree to correct for other plants the 
soil conditions which are unfavorable to them, but which 
in no way inhibit the luxuriant growth of the common 
sorrel. A study of other plants with this feature in mind 
will reveal other possibilities of a similar character. 

454. Miscellaneous effects of lime on plant diseases. — 
If lime is applied to acid soils, it creates a condition far 

295 



296 FERTILIZERS 

more favorable to development of potato "scab " than that 
which existed at the outset. This action is, however, by 
no means confined to lime, since sodium carbonate, barn- 




Limed Unlimed . Limed Unlimed 

Nitrate of soda Sulfate of ammonia 

Fig. 41. — Rye under Treatment. 

All fertilized alike with potash and phosphoric acid. A like amount of 

nitrogen was used in each case. 

yard manure, or other substances which are of an alkaline 
character have the same effect. For this reason lime 
should usually be introduced into a crop rotation after, 
rather than preceding, the potato crop. It is also impor- 



LIMING IN ITS RELATION TO PLANTS 297 

tant in all cases that the seed tubers should be treated with 
corrosive sublimate solution, as proposed by Bolley, or 
with formalin, in order to destroy any germs of the disease 
which may be present upon them. 

The dry spot of oats has also been recently observed in 
Europe to occasionally follow the use of lime. A some- 
what similar or identical disease, or a possible disturbance 
of physiological function of oat plants, has been observed 
on silt loam soil in occasional years at the agricul- 
tural experiment station of the Rhode Island State Col- 
lege. The evidence thus far at hand points rather to a 
disturbance of physiological functions. It is notable 
that the difficulty seems to depend, nevertheless, in a great 
measure upon the prevailing climatic conditions, for in 
certain seasons no injury has been observed. 

It was thought at first in Europe that the difficulty was 
confined to the moor (peat) soils, but it is now recognized 
as occurring also on sandy and clayey soils ; and Hudig 1 
believes it to be due to changes in the composition of the 
humus brought about by repeated applications of the lime, 
or by other physiologically alkaline fertilizers. 

The use of excessive amounts of lime or of other alkaline 
substances has been found to encourage a disease of to- 
bacco known as " tobacco root rot " 2 which is caused 
directly by a fungus (Thielavia basicola), the development 
of which may be hindered by the use of acidic fertilizers. 
It r has been suggested also that similar treatment may 
aid in combating certain diseases of the ginseng. 

A striking illustration of the lessening of disease by the 
use of lime is afforded by the " club-foot," " aubury," or 

i E. S. R., 25, 724; also Landw. Jahrb., Ifi (1911), 613-644. 
2 Circ. No. 7, Bureau of Plant Industry, U. S. Dept. of Agr. (1908) 
By Lyman J. Briggs. 



298 



FERTILIZERS 





Air-slaked lime Unlimed 

Fig. 42. — Treatment for Potato Scab. 

Complete fertilizer in both cases. 





Calcium sulfate Calcium chlorid 

Fig. 43. — Treatment for Potato Scab. 
Complete fertilizer in both cases. 



LIMING IN ITS RELATION TO PLANTS 299 

" finger-and-toe " disease of the cabbage, turnip, and other 
related plants of the Cruciferce family. This is accomplished 
by the employment of especially heavy applications of 
caustic lime immediately following a badly diseased crop, 
and again just before the growing of crops subject to the 
disease. 

455. Lime in connection with potato scab. — The ef- 
fect of lime in encouraging potato scab has been mentioned 
briefly elsewhere, but the subject is of such importance 
that it requires more than passing notice. 

Earlier ideas. — Prior to the year 1891 when Thaxter l 
discovered that potato scab was caused by a fungus 
(Oospora scabies Thaxt.), many observations had been 
made in Germany and elsewhere upon its appearance. 
Its occurrence had previously been attributed to lime and 
to many other substances, on the ground that they caused 
an irritation or injury to the surface of the tuber, and that 
in the attempt to recover from the injury the characteristic 
growth of scab devleoped. 

The work of Thaxter. — The laboratory investigations 
of Thaxter were supplemented by him by field trials of 
various substances for one season, in the course of which 
he found 60 per cent of scab when broken plaster and 
cement were used in the hill, whereas in alternate hills 
in which mixed fertilizer was used but 6 per cent of scab 
was found. Among other materials Thaxter also employed 
wood-ashes in the same manner as the broken plaster and 
cement. In this case but 7.5 per cent of scab resulted, 
whereas in the alternate hills without wood-ashes but with 
the mixed fertilizer 12.5 per cent of scab was observed. 
From the foregoing it is obvious that the results furnished 
no conclusive evidence of lime having promoted the devel- 

1 An. Rpt. Conn. Agr. Expt. Sta. (New Haven), 153-160. 



300 



FERTILIZERS 




Calcium carbonate Calcium ox 

Fig. 44. — Treatment for Potato Scab. 
Complete fertilizer in both cases. 




Calcium acetate 

Fig. 45. — ■ Treatment for Potato Scab. 
Complete fertilizer in both cases. 



Wood- 



LIMING IN ITS RELATION TO PLANTS 



301 



opment of scab, since they were negative with wood-ashes, 
which doubtless supplied much more carbonate of lime 
than was present in the broken plaster and cement. 

The work at the Rhode Island experiment station. — 
Upon the conclusion of Thaxter's work the matter was 
carefully investigated for a period of four years at the ex- 
periment station of the then Rhode Island Col ege o 
Agriculture and Mechanic Arts 1 with the result that 
slaked lime, wood-ashes, calcium carbonate, calcium oxa- 
late, calcium acetate, sodium carbonate, and barn-yard 
manure were all found to encourage the development of 
potato scab to a most serious extent, in case the causative 
fungus was present on the « seed » tubers or was already 
existent in the soil. On the other hand, calcium sulfate, 
calcium chlorid, sodium chlorid, and oxalic acid either 
failed to increase the scab or materially lessened it. By 
the use of a complete fertilizer, even with badly scabbed 
" seed " tubers, little or no scab ensued on soil which was 
quite acid. It was conclusively shown, also, m cases m 
which the soil was already badly contaminated by the 
fungus, and where it had been made favorable to potato 
scab by the use of alkaline manures or amendments, that 
treatment of the " seed " tubers exerted no appreciable 
protective influence against scab. 

Owing to the fact that in Thaxter's laboratory experi- 
ments the fungus failed to thrive well, not only on very 
acid, but also on very alkaline, media, it seems likely 
that the reason the wood-ashes failed to encourage scab, 
in his original field experiment, was that they were 
probably employed at rates far in excess of what would be 
usually applied to land, thus creating a strongly alkaline 
reaction, which may be just as protective against scab 

i Bulletins 26 (1893), 30 (1894), 33, (1895), and 40 (1896). 



302 FERTILIZERS 

as a condition of extreme acidity. This explains also 
the reason why broken plaster and cement should have 
encouraged scab, for the active lime therein must have 
been relatively too small to produce such a degree of 
alkalinity as would have been produced by the combined 
action of the carbonates of lime, magnesia, potash, and 
soda, all of which may have been present in the wood- 
ashes. 

456. Lime may be used and potato scab avoided. — 
Notwithstanding the tendency of lime to promote potato 
scab, it has been used periodically at the experiment sta- 
tion of the Rhode Island State College in several crop 
rotations in quantities amounting in the aggregate to 
about 3200 pounds of calcium oxid in a period of about 
twenty years, and yet without practical injury to the 
potato crops from scab. In this case, however, the lime 
is applied in the rotations immediately following the po- 
tato crops, at intervals of from three to six years, and the 
tubers are always treated with formalin or with corrosive 
sublimate solution before they are planted. The impor- 
tance of these precautions is obvious, in view of the fact 
that in certain of the experiments in Rhode Island, in 
which they were not taken, the scab fungus has survived 
saprophytically an interval of seventeen years without an 
intervening potato crop. 

457. Lime may cause injury to pineapples. — It has 
been reported by Gile x that when lime is present in sandy 
soils, in excess, it may be a cause of pineapple chlorosis. 
In such cases treatment of the leaves and soils with iron 
salts, though said not to be feasible from an economic 
standpoint, proved to be an effective antidote. The 
treatment of the leaves is in accord with recent experi- 

1 Porto Rico Agr. Expt. Sta., Bui. 11. 



LIMING IN ITS RELATION TO PLANTS 303 

ments showing that inorganic fertilizers can enter plants 
effectively through the leaf. 

458. The effect of lime on the size of potatoes. — Many 




Limed Unlimed 

Nitrate of soda 



Limed Unlimed 

Sulfate of ammonia 



Fig. 46. — Oats under Treatment. 
All fertilized alike with potash and phosphoric acid. A like amount of 
nitrogen was used in each case. 

experiments on an acid silt loam at the agricultural ex- 
periment station in Rhode Island, covering several years, 
have shown that liming frequently results in increasing 
the total crops of potatoes. This effect is, however, in- 



304 FERTILIZERS 

consequential compared with the great increase in the 
relative per cent of large tubers, a point which is of decided 
economic importance. 

459. Liming may hasten crop maturity. — The question 
of the influence of lime in hastening crop maturity has 
been much debated pro and con, probably for the reason 
that its effects are very different, depending upon the 
character of the soil, the crop, and other attendant con- 
ditions. 

If the physical condition of a soil were injured by liming, 
the growth of crops might be unduly prolonged; but if 
liming were to improve the physical condition, it would be 
expected that the maturity of the crops grown upon the 
soil would be hastened. 

If there were a lack in the soil of readily available nitro- 
gen, phosphoric acid, or potash, at the outset, to meet 
fully the plant requirements, the tendency would be to 
delay growth, and hence the final maturity of the crop. 
If, on the other hand, liming were to promote a sufficiently 
active ammonification and nitrification, or if it were to 
bring about a sufficient liberation of lacking mineral in- 
gredients to meet the complete needs of the plant, without 
material excesses, growth would follow rapidly from the 
outset, and maturity would probably be hastened. 

If a soil were very acid, and hence poorly adapted to the 
luxuriant growth of certain plants, liming would likewise 
be expected to hasten development and maturity. In this 
way one may account for the marked increase in large 
potato tubers mentioned previously. For similar reasons 
crops of onions have been observed to ripen from two to 
three weeks earlier on land which had been limed three 
times in the course of fifteen years than where the land had 
been limed but twice in the same interval. It has been 



LIMING IN ITS RELATION TO PLANTS 305 

observed in cases where liming failed, or practically failed, 
to increase the yield of Indian corn, that the maturity 
was nevertheless hastened from a week to ten days. 

On acid soils the effect of lime in hastening the maturity 
of cantaloupes and of kohl-rabi has often been found to 
be very marked. 




Limed Unlimed 

Nitrate of soda 



Limed Unlimed 

Sulfate of ammonia 



Fig. 47. — Wheat under Treatment. 
All fertilized alike with potash and phosphoric 
acid. A like amount of nitrogen was used in each 



i In case a soil were already abundantly supplied with all 
needed forms of plant food, and large quantities of nitrates 
were to be produced, as a result of liming, this additional 
supply would naturally have a tendency to prolong growth 
at the expense of maturity, just as was found by Voorhees 
to be the case when repeated applications of nitrate of soda 



306 



FERTILIZERS 



were made to tomato plants, in contrast to a single appli- 
cation at the outset. 

460. Soils needing liming for some plants ideally 
adapted to others. — Soils giving strong and quick re- 




Limed Unlimed 

Nitrate of soda 



Limed Unlimed 

Sulfate of ammonia 



■Fig. 48. — Barley under Treatment. 
All fertilized alike with potash and phosphoric acid. A like amount 
of nitrogen was used in each case. Comparisons with Figs. 41, 46, and 
47 show that barley is more helped by liming than wheat, oats, or rye. 



actions with blue litmus paper and with ammonium 
hydroxid are frequently highly toxic to certain very sen- 
sitive plants, even though the soils have not been fertilized 
at all for many years with either chemical fertilizers 
or barn-yard manure other than perhaps the occasional 



LIMING IN ITS RELATION TO PLANTS 307 

dropping of dung by horses or cows. It is not to be sup- 
posed that the ill effect upon certain plants is necessarily 
due in all cases directly to soil acidity, but perhaps chiefly 
in many cases to toxic iron compounds, toxic organic 
substances, or other deleterious compounds accompanying 
the lack of basic substances, or arising in consequence 
thereof, which are oxidized, catalysized, or otherwise de- 
stroyed as a result of the application of lime. 

461. Details concerning the lime requirements of dif- 
ferent plants. — It is not safe in any event to generalize 
from experimental results secured with one, or even with 
several, plants in regard to the lime requirements of other 
plants in their relation to the soil. This is well illustrated 
by the fact that a soil rendered so toxic by the long-con- 
tinued application of ammonium sulfate as to absolutely 
inhibit the growth of the poppy, lettuce, beet, canta- 
loupe, asparagus, cress, onion, barley, clover, and a whole 
series of other agricultural and ornamental plants will yet 
produce better plants of the common sorrel, cranberry, or 
Silene orientalis than it will after the condition, so highly 
unfavorable to most plants, had been corrected by liming. 
With only the latter plants in mind, and provided one had 
not experimented with others, the natural assumption 
might be that agricultural soils are never so acid or so 
charged with toxic substances as to interfere with the 
growth of plants, for the worse the condition becomes for 
certain plants, within reasonable limits, the better certain 
others seem to thrive. Similarly, on the other hand, cer- 
tain plants are best suited by conditions of alkalinity or 
salinity which are totally destructive to the great majority 
of agricultural plants. 

On account of a lack of sufficient appreciation of these 
conditions, the agricultural press and even scientific pub- 



308 FERTILIZERS 

lications often contain statements to the effect that legumes 
are in great need of liming, in order that they may develop 
root nodules and properly assimilate atmospheric nitrogen. 
Nevertheless, the Southern cowpea, serradella, and certain 
of the lupines are likely to be injured by heavy liming. 
Other legumes may possibly be injured under the same 
conditions, whereas the alfalfa and winter vetch suffer 
seriously, for lack of lime, even where clover will still grow 
with moderate success. 

Not only the lupines (Lupinus), but also the beans 
(Phaseolus), differ widely among themselves as to their 
requirements for lime in its amendatory capacity. 



CHAPTER XXI 

GYPSUM AND WASTE LIME FROM INDUSTRIES 

Recently gypsum has been employed in the United 
States to a smaller extent than formerly, whereas the use 
of ground limestone, burned lime, slaked lime, and waste 
lime from certain industries has increased. 

462. Early use of gypsum. — Gypsum (land plaster or 
calcium sulfate) has been used as a fertilizer since the time 
of the earliest Greek and Roman writers. Much mystery 
surrounded its action in earlier times, which has been re- 
moved by modern discoveries in agricultural science. It 
is now available as ground gypsum and as a by-product 
of the manufacture of double superphosphate. 

463. The source of some of the gypsum in soils. — In 
certain localities considerable calcium sulfate is present in 
soils naturally, and since the advent of superphosphates it 
has been added in that form to the land in considerable 
quantities, with but little thought on the part of the user 
that it was present in the usual commercial fertilizer 
which he was applying. 

Gypsum has also been added to soils incidentally, in 
some cases, in kainit, which is used by itself or as a fre- 
quent constituent of ready mixed commercial fertilizers. 

The effect of gypsum and lime on clover and other plants. 
— In Europe, generally, gypsum has long been considered 
as a specific for clover ; and in many cases it has been 
found to give much better results than lime. Indeed, 

309 



310 



FERTILIZERS 




Storer l cites several such 
cases and mentions in the 
same connection that Gas- 
parin found it to work well 
on a soil containing 20 per 
cent and more of lime. 

In experiments at the 
agricultural experiment 
station of the Rhode Is- 
land State College it was 
found, on an acid silt loam 
soil, that, notwithstanding 
a striking gain in beets and 
clover resulting from the 
use of gypsum, the employ- 
ment of the same quantity 
of calcium oxid in air- 
slaked lime gave far better 
results. 

In order to throw light 
upon other similar discrep- 
ancies in the use of these 
substances, it should be 
pointed out that Gasparin 
was dealing with a soil well 
supplied with lime, in whi ch 
the general conditions were 
not unfavorable to the 
growth of the particular 
crop concerned, whereas in 
the experiment made in 



1 Agriculture, etc., 
(1897), 326. 



Vol. 



GYPSUM AND WASTE LIME FROM INDUSTRIES 311 

Rhode Island the soil was a silt loam essentially devoid 
of carbonate of lime and so deficient in bases as to 
quickly and intensely redden blue litmus paper and to 
yield large quantities of humus (" matiere noire " of 
Grandeau) upon extraction with dilute ammonium 
hydroxid, without previous extraction with hydro- 
chloric acid. It was also shown that applications of 
sodium carbonate, potassium carbonate, and burned 
magnesia very largely corrected the condition of this soil 
for beets and other plants, but that the corresponding sul- 
fates were of little or no avail. It is evident, therefore, 
that in Gasparin's experiment neutralization of the soil 
was not needed, and gypsum was helpful probably chiefly 
because of the liberation of potash or possibly by virtue 
of supplying sulfur, both of which clover greatly needs. 
Gypsum may nevertheless also have been useful in liber- 
ating magnesia and phosphoric acid or in counteracting 
an improper relation between lime and magnesia, if such 
existed. 

The possibility of some indirect action in the experi- 
ment by Gasparin is well illustrated by experiments by 
Boussingault in which the application of gypsum resulted 
in raising very greatly, not only the percentage of lime in 
clover, but also the content of potash, magnesia, phos- 
phoric acid, and sulfuric acid. 

In the Rhode Island experiment generous applications 
of complete fertilizer were made in both cases, which 
would naturally have lessened any benefit arising from the 
possible liberation of plant food ingredients of the soil. 

464. Gypsum poorer than lime on acid soils. — The 
chief factor causing the superior action of the slaked lime 
in Rhode Island was the fact that the prime difficulty with 
the soil was its acidity, which the lime could neutralize at 



312 FERTILIZERS 

once, but which the gypsum could correct but little, if at 
all, until by possible processes of reduction some of the 
sulfate had been transformed into calcium sulfid and this 
in turn into calcium carbonate through the action of car- 
bonic acid. 

465. Gypsum may yield calcium carbonate in the soil. — 
The formation of calcium carbonate from gypsum is in- 
dicated by the following equations : — 

(1) CaS0 4 + 2 C = 2 C0 2 + CaS 

calcium carbon carbon calcium 
sulfate dioxid sulfid 

(2) CaS + C0 2 + H 2 = CaC0 3 + H 2 S (volatile) 

calcium carbon water calcium hydrogen 

sulfid dioxid carbonate sulfid 

It must be remembered, however, that these changes 
take place under anaerobic conditions, which are not 
likely to be vigorously maintained for a great length of 
time in fairly open, well-drained soil which is in good tilth. 

466. Gypsum may furnish lime or sulfur as plant food. 
— It is possible that cases may occur where gypsum is 
useful by virtue of supplying either lime or sulfur to the 
plant, in the capacity of a plant food ingredient, but in 
general the explanation is more properly to be sought in 
an indirect manurial action, by virtue of the liberation of 
other plant food elements. 

467. Factors determining the choice between gypsum 
and lime. — When dealing with soils which are acid and 
with plants readily subject to injury by such acidity or 
by the toxic substances which often accompany it, either 
slaked lime or calcium carbonate is likely to prove more 
effective as a soil amendment than gypsum. In the case, 
however, of nearly neutral, neutral, or alkaline soils, or of 



GYPSUM AND WASTE LIME FROM INDUSTRIES 313 

plants that find therein optimum conditions, as concerns 
their chemical reaction, it is probable that gypsum will be 
found to act better than the other compounds of lime. 

468. Gypsum as a retainer of ammonia. — Whereas 
much weight was formerly attached to gypsum as an agent 
for changing the ammonia of ammonium carbonate into 
ammonium sulfate, whereby its volatilization might be 
avoided, it has been found that much moisture is necessary 
to the change, and furthermore the reaction is only partial 
and even then reversible, so that the importance of gypsum 
in this connection, under many of the conditions practi- 
cally to be dealt with, seems to have been much overes- 
timated. 

469. Methods of applying gypsum. — For clover it has 
generally been found to be a good practice to apply the 
gypsum to the moist leaves when the plants are only a 
few inches high. Similarly, it has been applied with good 
results to potatoes by scattering it along the top of the 
drill after the plants are well up and immediately before 
cultivating them. It may of course be spread broad- 
cast, and then be harrowedinto the soil, especially before 
seeding to clover and before the planting of other crops. 

470. Gypsum as an oxidizing agent. — Mention has 
been made of the reduction of calcium sulfate to calcium 
sulfid, and it should be recognized that in connection with 
this process gypsum plays the role of an oxidizing agent. 
It furnishes the oxygen for the destruction of the vege- 
table matter, which takes place through the intervention 
of the microorganisms of the soil. 

471. Gypsum may sometimes aid nitri cation. — 
Owing to the capacity of gypsum to react with ammonium 
carbonate to form ammonium sulfate and calcium car- 
bonate, it has been shown by Warrington to be effective 



314 FERTILIZERS 

in promoting nitrification in liquid manure or in manure 
heaps, where the reaction is too alkaline at the outset 
for nitrification to begin. 

472. Gypsum a renovator of alkaline soils. — Gypsum 
has been shown by Hilgard and others to be an efficient 
substance for counteracting black alkali (sodium carbon- 
ate) in consequence of its reacting with it to produce 
sodium sulfate and calcium carbonate, whereby the al- 
kalinity is greatly reduced. 

473. Effect of gypsum on the solubility of lime. — It 
has been shown by Cameron and Bell 1 that the solubility 
of gypsum is depressed in an increasing degree as the 
amount of lime (CaO) in the solution is increased, where- 
as with increasing amounts of gypsum in the solution the 
solubility of lime seems to be nearly the same as in pure 
water. 

474. Gas-lime and lime from other industries. — " Gas- 
lime," or " gas-house lime " as it is sometimes called, 
should lie exposed to the air for some time in order to 
effect the destruction of certain poisonous substances, 
before it can be applied to the land with safety. The 
lime in the processes of purifying the gas is changed very 
largely into calcium sulfate, and hence it cannot perform 
the same functions as slaked lime, burned lime, or calcium 
carbonate. 

The lime waste from acetylene lighting plants is essen- 
tially hydrated lime, and it has been used agriculturally 
with good results. The same is true of the waste lime 
from beet-sugar factories and from other industrial works. 

It is always a wise precaution to have waste factory 
products examined by an agricultural experiment station 

1 Jour. Am. Chem. Soc, 28 (1906), 1220; Bui. No. 33, Bur. of Soils, 
U. S. Dept. of Agr. (1906) ; Jour. Phys. Chem., 11 (1907), 273. 



GYPSUM AND WASTE LIME FROM INDUSTRIES 815 

before attempting to utilize them for manurial purposes, 
for the reason that factory processes are subject to frequent 
changes, and the presence of some one or more substances 
toxic to plant life is not unusual in the residues from cer- 
tain industries. 



CHAPTER XXII 

MAGNESIA AS A FERTILIZER 

In 1851 E. von Wolff * pointed out the beneficial effect 
of magnesia upon plant growth, although Mulder be- 
lieved it was merely due to its liberation of other plant 
foods. 

475. Functions of magnesia in the plant. — It was 
shown by the work of Schmiedenberg 2 that magnesia 
was possibly of importance in connection with the forma- 
tion of the albuminoids. At present, however, magnesia 
is not believed to play a direct role in connection with 
protein formation. 

According to E. von Raumer 3 magnesia performs 
useful functions in connection with the translocation of 
starch, though in this respect potassium is now known to 
be particularly important. 

It has been asserted by Loew and by Hilgard 4 that 
magnesia serves in the plant as a carrier of phosphorus, 
where, according to Hilgard, it exists as dimagnesic-hydric 
phosphate. The fact that more magnesia is present in 
oily than in starchy seeds, supports this view, since 
lecithin, which is rich in phosphorus, is formed in cells 
rich in oil. It is furthermore stated by Reed that there 

i Erdmann's Jour., 51 (1851), 15. 

2 Zeits. f. Physiolog. Chem., 1, 205. 

3 Die landw. Vers.-Sta., 29, 279. 

4 Soils, etc. (1906), 382. 

316 



MAGNESIA AS A FERTILIZER 



317 



is often a very definite relation between the magnesia 
and the vegetable oils. It is also of interest to note that 
Ville found, when magnesia was omitted, that the yield of 
wheat fell from 337 to 123 grains. 

According to Bretfield 1 an increase in the dry weight of 
plants is impossible in the absence of magnesia. In 
experiments by Dassonville, 2 with magnesium sulfate, 




No lime Ground magnesian limestone Slaked Lime 

Fig. 50. — Alfalfa on Farm. 
All fertilized alike with potash and phosphoric acid. Quantities of lime 
having the same total neutralizing value were used in each case. 

it was found that, though delaying the growth of certain 
legumes at the outset, it became finally indispensable. 
The participation of magnesia in some of the most impor- 
tant synthetic processes of the plant is asserted by Stras- 
burger, Noll, Schenck, and Schimper. 3 

In brief, no one now questions that magnesia is essential 
to plant growth. 

476. Conflicting ideas as to the action of magnesia. — 
According to Atterberg, 1 the compounds of humus 



1 Pflanzenphysiologie (1884), 135. 

2 Revue generate de Botanique, 8 (1896), 331; Abs. Jahresb. f . 
Chem. (1896), 260. 

3 A Textbook of Botany, translated by Porter (1898), 173. 



Agr. 



318 



FERTILIZERS 



with lime are less soluble than those of humus and mag- 
nesia. 

It was asserted by Stutzer 2 as late as 1893 that soils 
usually contain sufficient magnesia to meet plant require- 
ments, yet D. Meyer, 3 for example, attaches special value 




12 3 4 

Fig. 51. — Treatment of Oats. 
1. Unlimed. 2. Calcium chlorid in 1894 and 1895. 3. Same as 2, with 
addition of caustic magnesia in 1897. 4. Same as 2, with addition of slaked 
lime in 1897. All fertilized alike with complete fertilizer. 

to magnesian lime as compared with the high calcium 
limes, in connection with the growth of certain legumes; 
and Larbaletrier and Malpeaux report the use of magne- 
sium sulfate as advantageous for beets, for some years, in 
the Department of Pas-de-Calais, France. Similar results 
are also recorded by Stockhardt, in Saxony, and like 

1 Svenska Mooskultur-foreningenstidschrift (1891), 121, 122; Abs. 
Centralb. f. Agrik. Chem, 21, (1882), 298, 299. 

2 Leitfaden der Diingerlehre, p. 16. 

3 Landw. Jahrb., 29 (1900), 961. 



MAGNESIA AS A FEETILIZEB 319 

instances may be cited from experiments in Rhode Island, 1 
and elsewhere in the United States. 

It has long since been observed that experimenters 
in different localities have sometimes secured quite op- 
posite results from the use of magnesia, as, for example, 
in the case of the good results secured by Ville when it 
was used for wheat and the ill effect on wheat noted by 
Passarini. 2 

It has been pointed out by Storer that Tennant noted a 
poisonous action of caustic magnesia, yet in recent ex- 
periments at the Maryland experiment station caustic 
magnesia at the rate of 1400 pounds per acre gave in 
certain instances better results than the same amount of 
calcium oxid in ground oyster shells. In fact, many 
similar conflicting instances might be cited. 

It has been stated that Von Raumer, in 1883, pointed 
out the necessity of a proper relationship of lime to mag- 
nesia in connection with plant growth ; and Knop called 
attention at an early date to the fact that in water-culture 
experiments certain calcium, potassium, or ammonium 
salts were capable of counteracting the ill effects of an 
excess of magnesia, and he suggested the applicability of 
lime as an antidote for magnesia in field culture. Many 
other investigators have found lime an antidote for an 
excess of magnesia in field practice. Later, a theory was 
advanced by Loew 3 which may explain, in many cases, 
this interesting and important fact. 

477. Loew's theory concerning magnesia. — In brief, 
Loew holds "that a calcium protein compound partici- 

i An. Rpt. R. I. Agr. Expt. Sta., 17 (1903-1904), 230-234. 

2 Bol. Scuolo Agr., 3 (1895), 140-142 ; Abs. Jour. Chem. Soc. (London), 
72, No. 142, II, 587. 

3 Die landw. Vers.-Sta., 41, 466-475 ; also Flora (1892), 368-394 ; Bui. 
18, U. S. Dept. of Agr., Div. of Veg. Phys. and Path. (1889), 42. 



320 



FERTILIZERS 




o 

s .5 

* 2 

H S 

ft T3 

o £ 



& a ^ 



a m 

O to 

s h 

. .3 

- eg cs 



•2 'a 

2 « 






pates in the organized 
parts of the nucleus 
and chlorophyl 
body," and that 
when magnesium 
salts of the stronger 
acids are made avail- 
able to the plant, 
the lime as the 
stronger base would 
" combine with the 
acid of the mag- 
nesium salt, while the 
magnesia would enter 
into the place which 
the lime had occu- 
pied in the organized 
structure ; the ca- 
pacity for imbibition 
would thereby be 
altered and a disturb- 
ance of its structure 
would result which 
would prove fatal. 

" On the other 
hand, judging [from 
the laws of the action 
of masses, it would 
naturally be inferred 
that an excess of lime 
salts would remedy 
the evil effects by 
making the reverse 



MAGNESIA AS A FERTILIZER 321 

process possible." It is not to be assumed, however, 
that all cases of injury arising from the use of magnesia 
are due to the reason given by Loew and his various co- 
workers, for other factors often come into play. It ap- 
pears probable, nevertheless, that there are certain fairly 
definite relations between lime and magnesia which are 
best for given kinds of plants, and yet for other plants 
they may be widely different. The recent work by Gile 
shows that in some cases the importance of the very 
close and definite relationship may have been overesti- 
mated. The investigation of this question is, however, 
yet in its infancy. 

There has unquestionably been too great a tendency to. 
explain cases of injury arising from the use of magnesium 
salts on the basis of Loew's theory, for in many cases some 
other explanation harmonizes far better with the observed 
facts. 1 These attempts to support the theory of Loew 
by frequent unwarranted claims have resulted in awaken- 
ing unnecessary fear of magnesia poisoning, even in 
regions where magnesia is not present in soils in undue 
proportions as compared with lime, and where its applica- 
tion is often followed by good results. 

478. The ratios of lime and magnesia in different soils. 
— It has been asserted by D. Meyer 2 that soils with an 
especially high content of magnesia, as compared with the 
lime, are quite exceptional ; yet Loew 3 cites analyses of 
twenty soils from different parts of Japan in which the 
magnesia exceeds the lime by from two to five times, and 
the relations of the two in the soils of Japan have been 
found to range from traces of lime associated with 0.475 

1 An. Rpt. R. I. Agr. Expt. Sta., 17 (1903-1904), 221-260. 

2 Landw. Jahrb. (1904), Heft 3. 

3 Ibid. (1905), 133. 

Y 



322 



FERTILIZERS 



per cent of magnesia to such limits as 1.618 per cent of 
lime and 6.307 per cent of magnesia. Other analyses of 
Japanese soils are also cited in which quite the opposite 
relation was found to exist. 

Magnesia has also been found in excess of the lime in 
certain of the soils of Ohio, which have been greatly helped 
by liming, yet the benefit in this case may well be 
due chiefly to other effects than the correction of an un- 
favorable ratio between lime and magnesia. Indeed, 




Fig. 53. — Clover, Redtop, and Timothy, prominent in the Order 

Named. 
Hydrated magnesian lime with high magnesia content. "Complete" 
fertilizer. Seeded to timothy, redtop, and clover, the same as in Figs. 
52, 54, and 55. 



even Loew {ibid., p. 135) calls attention to the neutralizing 
value of both calcium carbonate and magnesium carbon- 
ate, and to their frequent beneficial action, in this capac- 
ity, upon the bacterial flora of the soil, which effects, he 
admits, may in certain cases be so great as to obscure the 
physiological effects due to correction of the calcium- 
magnesium ratio. He also adds that otherwise in soils 
containing about equal quantities of lime and magnesia 
the yield of cereals would be depressed by an application 
of either. 

In order to arrive at the lime and magnesia available 



MAGNESIA AS A FERTILIZER 323 

in the soil, Loew prefers an extraction of the fine earth 
with 10 per cent hydrochloric acid rather than with a 10 
per cent solution of ammonium chlorid, which was em- 
ployed by Meyer. 

479. Variations in magnesia content of different parts 
of the same plant. — Instances are cited by Loew 1 of 
certain seeds in which there are found one hundred mole- 
cules of magnesia to seventeen of lime, and yet in the 
leaves there were two hundred and twenty-four molecules 
of lime to one hundred of magnesia. 

480. Concerning the alleged toxic action of magnesium 
chlorid. — It was suggested by Knop that in certain 
soils sulfate of potash should be employed rather than 
muriate of potash on account of the possibility that 
magnesium chlorid might otherwise be formed, which 
Knop regarded apparently as a positive plant poison. 

According to the theory of Loew, magnesium chlorid 
would be expected to have a toxic action upon plants, at 
least whenever the lime was deficient. In fact, he states 2 
that " calcium and magnesium chlorid have an injurious 
effect upon plants, probably on account of the liberation 
of hydrochloric acid in cells, this not being assimilated 
like nitric and sulfuric acid and therefore accumulating 
to a noxious degree." 

It has been stated by L. von Wagner 3 that calcium and 
magnesium chlorids are not good for potatoes and beets. 

It is obvious that excessive a'hiounts of magnesium 
chlorid, like other salts, must inevitably be injurious 
to plant life ; the degree of injury depending upon the 
kind of plant and the concentration of the salt solution. 

1 Die landw. Vers.-Sta., 4-1 (1892), 473. 

2 Bui. 18, U. S. Dept. of Agr., Div. of Plant Phys. and Path., 18. 

3 Pfianzen-Produktions-Lehre (1874), 336. 



324 FERTILIZERS 

A study of the effect of magnesium chlorid was made 
by Wheeler and Hartwell 1 on a silt loam containing about 
0.57 and 0.21 per cent, respectively, of lime and magnesia 
soluble in strong hydrochloric acid, as determined by the 
Hilgard method of soil analysis. The land had been 
planted to Indian corn for several years, without fertilizer 
or manures, until it would no longer produce a crop over 
6 inches high in the course of a whole season. The 
experiments were made in galvanized iron pots 18 inches 
in diameter and 26 inches deep, with the bottoms sloping 
to an opening in the center. The pots were set in soil 
nearly to their tops over drain tile, which insured normal 
conditions of temperature and prevented the backing up 
of water into them from the surrounding soil. The first 
two years all of the pots received acid phosphate, nitrate 
of soda, and muriate of potash, and the third year dried 
blood, basic slag meal, and potassium-magnesium car- 
bonate (a product of the German potash works). The 
average yield of barley plants per pot the first year, with- 
out further treatment, was 43.7 grams, and upon the addi- 
tion of 19.2 grams of hydrous magnesium chlorid per pot 
the yield was 46.5 grams. By the use of 110 grams of 
calcium carbonate per pot in addition to the magnesium 
chlorid the average yield was raised to 67.9 grams; but 
when caustic magnesia was added at the rate of 44 grams 
per pot in place of the calcium carbonate, the average 
yield fell to 6.1 grams. 

The following year the application of magnesium chlorid 
was repeated, and spring rye was grown. The average 
yield with magnesium chlorid was 51.3 grams; the yield 
where calcium carbonate had also been applied, the pre- 
vious year, was 55.8 grams ; and where caustic magnesia 

1 An. Rpt., R. I. Agr. Expt. Sta., 15 (1901-1902), 295-304. 



MAGNESIA AS A FERTILIZER 325 

replaced the calcium carbonate, the yield was now 49.7 
grams. The toxic action of the caustic magnesia, ob- 
served the first year, had now practically vanished. It 
was found that the addition of magnesium carbonate 
at the rate of 59.2 grams per pot, where the caustic 
magnesia had been applied the year before, resulted in 
a depression of the yield to 41.4 grams. This second 
year the check pots to which no magnesia had been 
added in any form gave an average yield of but 3.7 
grams. 

The third year the crop was oats, and the average yield 
with magnesium chlorid was 84.4 grams of oat plants per 
pot. Where calcium carbonate had been added two years 
before, the average yield was now 79.4 grams ; that 
where caustic magnesia was used two years before was 
87.9 grams ; and the yield where caustic magnesia was 
used two years before, and magnesium carbonate a year 
before, was 82.5 grams. It is of special interest to note 
that the yield of the check pots as a result of using a basic 
magnesian fertilizer was now 88.7 grams. The magne- 
sium chlorid had not in this case proved materially or 
positively toxic, since the differences are within the 
reasonable limit of error. In view of the improvement 
in yield from the use of calcium carbonate and the injury 
from caustic magnesia the first year, it might have been 
assumed, on the basis of Loew's theory, that the lime had 
been helpful by virtue of counteracting an undue propor- 
tion of magnesia ; yet such a conclusion is impossible in 
view of the excellent results in every case in the last year, 
where magnesium salts were used as additions to the 
magnesium chlorid and the regular fertilizer. It has 
since been shown by field experiments that this soil had 
finally become so acid as to inhibit almost absolutely the 



326 FERTILIZERS 

growth of timothy, clover, and barley, until the condition 
was corrected by the addition of calcium carbonate, potas- 
sium-magnesium carbonate, burned dolomite or slaked 
lime (slightly magnesian). This fact accounts for the 
poor results of the second year in the check pots when 
muriate of potash and acid phosphate were used, and 
also for the toxic action of ammonium chlorid when used 
in an experiment under the same conditions as magnesium 
chlorid. This also explains the effect, the first two years, 
of calcium carbonate in more than counteracting the tox- 




Fig. 54. — Redtop. (Clover and Timothy lacking.) 

Complete fertilizer. No lime. Seeded to timothy, redtop, and clover, 

the same as in Figs. 52, 53, and 55. 

icity of the ammonium chlorid, and also the effect of the 
basic fertilizer made up of basic slag meal, dried blood, and 
potassium-magnesium carbonate, in correcting, in all 
cases, the conditions in the check pots in the third year. 

The foregoing results show that magnesium chlorid 
is less toxic on certain soils than ammonium chlorid; 
and still other experiments with the same soil indicate 
that it is far less toxic than calcium chlorid. 

481. Danger from using caustic magnesia and burned 
and hydrated magnesian lime. — The preceding results 
show that caustic magnesia was toxic at first when it 
was used in large quantities, even on a soil evidently in 



MAGNESIA AS A FERTILIZER 327 

slight need of magnesia, but that when sufficient oppor- 
tunity had been afforded for it to become carbonated, it 
became useful. It is probably on this account that special 
care must be taken in employing a hydrated, air-slaked, 
or burned magnesian lime immediately before planting 
a crop, unless great care is taken to limit the quantity 
used to moderate applications, and to most thoroughly 
incorporate it with the soil. Such danger is obviously 
greater on light, sandy, and gravelly soils, lacking in 
moisture and vegetable matter, and less on heavier soils 
rich in vegetable matter, especially if they are of an acidic 
character. 

482. The solubility of magnesium carbonate in its 
relation to practice and experiment. — According to 
Comey, 1 magnesium carbonate is more soluble than cal- 
cium carbonate in water, carbonated water, and in am- 
monium chlorid. It has also been shown by Tread well 
and Reuter that one liter of water will hold only 0.385 gram 
of calcium bicarbonate in solution, but that the same 
amount of water will hold in solution at one time, not 
only 1.954 grams of magnesium bicarbonate, but also 
0.715 gram of magnesium carbonate. For this reason 
there is much more danger of injury from heavy applica- 
tions of burned and slaked magnesian lime than from the 
pure lime, especially on soils but little in need of basic 
applications, and for plants which are particularly suscep- 
tible to such injury as may arise in consequence of the 
creation of an alkaline reaction in the soil solution. Not- 
withstanding that these figures may apply to magnesium 
carbonate, which is formed by the taking up of carbonic 
acid by slaked magnesian lime, it is doubtless not true of 
the magnesium carbonate in natural magnesite, dolomite, 

1 A Dictionary of Chemical Solubilities, London and New York, 1896. 



328 FERTILIZERS 

or highly magnesian limestone ; for Hilgard x has pointed 
out that magnesia in its native combinations leaches less 
rapidly from soils, than lime, indicating that the relative 
solubilities of artificial carbonates may be quite the re- 
verse of the natural compounds. In fact, the mineral 
magnesite (magnesium carbonate) is said to be probably 
insoluble in water and not to be affected by boiling with 
water or with aqueous solutions of alkaline carbonates. 2 
Experiments conducted under the direction of B. L. Hart- 
well, at the request of the writer, have also shown that 
ground magnesian limestone, sufficiently fine to pass a 
sieve with 50 meshes to the linear inch, was much less 
soluble in carbonated water maintained in a state of 
saturation than ground limestone passing a sieve of the 
same mesh. In fact, the solubility of the latter was ap- 
proximately three times as great as the solubility of the 
former. 

If, therefore, quick action is necessary, magnesium car- 
bonate, if formed recently from burned magnesian lime, 
would be expected to correct undue acidity of soils rather 
more quickly than calcium carbonate ; but natural mag- 
nesite, dolomite, or magnesian limestone might accom- 
plish it less quickly than natural carbonate of lime. 

It has been shown by H. Ley 3 that neutral salts check or 
prevent dissociation, hence magnesium carbonate as well 
as calcium carbonate may be expected to act favorably 
on acid soils in preventing dissociations of compounds 
possessing ions of a character injurious to plant growth. 
On the other hand, the high solubility of magnesium 



1 Soils, etc. (1906), 383. 

2 Davis, Jour. Soc. Chem. Ind., 25 (1906), 788; cited from Cameron 
and Bell, Bui. 49, Bur. of Soils, U. S. Dept. of Agr., 59. 

3 Ber. d. deut. chem. Gesell., 30, 2192. 



MAGNESIA AS A FERTILIZER 329 

carbonate, such as would be likely to be formed quickly 
from burned magnesian limestone in the soil water, and 
the possibility of creating by its presence alkaline condi- 
tions unfavorable to certain plants, has been very fre- 
quently neglected or ignored in farm practice and also in 
experimental work. In consequence, in certain instances 
very erroneous conclusions have doubtless been drawn. 
In fact, no experimenter can afford to neglect the possibility 
of such effects any more than he should, for example, the 
possible influence of such compounds upon the ionization of 
other salts, upon the bacterial life, or upon the physical 
character of the soil. 

483. Ranges in lime and magnesia content of plants 
without material differences in yield. — It was found by 
Wheeler and Hartwell in pot experiments with spring rye 
in which the average yields of rye plants per pot were 
50.5 and 51.3 grams, respectively, that in the former case, 
in which calcium carbonate was employed, the ratio of 
lime to magnesia was 6.3 to 1 ; whereas in the second 
instance, where magnesium chlorid had been applied, the 
ratio of lime to magnesia was 1.5 to 1. Results with 
mangels were also secured in connection with which, in 
addition to the regular fertilizer, caustic magnesia, sodium 
carbonate, and air-slaked lime were employed. When 
caustic magnesia was added to the usual fertilizer, the 
yield was 126.3 grams of air-dried mangel " roots," and 
the ratio of lime to magnesia was 6.4 to 1 ; when sodium 
carbonate was added, the yield was 131.3 grams, and the 
ratio of lime to magnesia was 1.6 to 1 ; when slaked lime 
was used instead of the caustic magnesia or sodium car- 
bonate, the yields in two cases were 148.2 and 132 grams 
and the ratios of lime and magnesia 4.4 to 1 and 3 to 1, 
respectively. Without further addition than that of the 



330 FERTILIZEBS 

regular fertilizer^the yield was 91.3 grams and the ratio of 
lime to magnesia was 4.2 to 1. 

Attention has been called elsewhere to the fact that 
plants may be physiologically relieved of certain excesses 
of lime by its crystallizing out within them as insoluble 
calcium oxalate and in some cases exteriorly as calcium 
carbonate. The former disposition is impossible in the 
case of magnesia, because of the solubility of the mag- 
nesium oxalate. It must be evident, therefore, that in 




Fig. 55. — Extreme Left, Redtop and Weeds. (No Clovek nor 

Timothy.) 

No lime. No fertilizer. Seeded to timothy, redtop, and clover, the 

same as in Figs. 52, 53, and 54. 

any discussion of the ratios of lime and magnesia in plants, 
the possibility of such storing away of some of the lime in 
insoluble, and hence in inactive form, must be taken into 
consideration; yet in the instance here considered, it 
does not seem probable that this factor could have had 
much influence on the relation of the two. It appears, 
therefore, as concerns the ratios of lime and magnesia within 
the plant, that there may be in some cases very wide varia- 
tions without an accompanying difference in yield. 

484. Desirable lime and magnesia ratios in soils and 
culture solutions. — According to Loew, 1 a relation of 2 of 

1 Circular No. 10 (1909), Porto Rico Agr. Expt. Sta. 



MAGNESIA AS A FERTILIZER 331 

lime to 1 of magnesia in soils is to be desired, because it 
stands between that which is best for cereals, on the one 
hand, and for the legumes on the other; he points out, 
however, that the relative availability of the lime and 
magnesia present in the soil may nevertheless change 
these ratios materially, a difference not revealed by his 
chemical method of determining them. Furthermore, 
these generalizations, especially as to the legumes, may 
be hasty and subject to material modification, depending 
upon the individual legume concerned. 

It has been established experimentally by Furuta and 
Katayama x that the most advantageous ratio of lime to 
magnesia is 1 to 1 for rice and oats, 2 to 1 for cabbage, 
and 3 to 1 for buckwheat. It appears, in other words, in 
accord with the relatively greater amount of lime in the 
leaves, and of magnesia in the seeds, that plants with a 
great leaf surface may require relatively more lime. 

It was found by Bernadini and Corso that the best 
ratio of lime and magnesia for maize was 2 to 1 ; for oats 
in water-culture it was 1 to 1 ; and in soil culture 2 to 1 was 
permissible ; but a depression in yield resulted with a ratio 
of 3 to 1. It was noted by Takeuchi that a decrease of 
two-thirds resulted in the growth of oats, when the ratio of 
lime to magnesia was changed from 1 to 1, to 10 to 1. 

The experiments of Aso, Bernadini, and Corso, and 
likewise of Konowalow, have indicated the proper lime- 
magnesia ratio for rice, wheat, rye, and barley to be 1 to 1. 
For onions, Katayama found 2 of lime to 1 of magnesia 
the best ratio. For leaf production, in the case of mul- 
berry trees, Aso established the ratio of 3 of lime to 1 of 
magnesia. 

1 Bui. Col. of Agr., Tokyo, 4, Nos. 5 and 6. 



332 FERTILIZERS 

For flax, Nakamura gives the proper ratio of lime to 
magnesia as 1 to 1. 

Experiments by Daikuhara 1 with a soil having 0.64 
per cent of lime and 1.91 per cent of magnesia indicated 
that a ratio of 3 of lime to 1 of magnesia is unfavorable 
to beans, buckwheat, tobacco, and the cereals. 

The recent work by Gile gives evidence of frequent wide 
variations in the lime-magnesia ratios of soils, without 
unfavorable effects on the plants. 

485. Sources of magnesia. — Magnesia is available for 
fertilizer purposes in several different forms : — 

(1) Magnesite, magnesium carbonate (MgC0 3 ), occurs as 
a native mineral in California, and elsewhere in the United 
States, and it is found in considerable quantities in Eu- 
rope. It is said to be insoluble in pure water and to be 
exceedingly resistant to carbonic acid. 

(2) Dolomite is a whitish-opaque calcium-magnesium 
carbonate containing about 47.6 per cent of magnesium 
carbonate, the remainder being carbonate of lime. 

(3) Magnesian limestone is one in which a part of the 
calcium carbonate is replaced by magnesium carbonate in 
proportions ranging from traces of magnesium carbonate 
to essentially the quantities present in dolomite. 

(4) Dou le manure salt (double sulfate of potash and 
magnesia) , also referred to as low-grade sulfate of potash, 
and kainit. The latter contains magnesium sulfate, and 
also carries considerable quantities of magnesium chlorid. 
These salts and kieserit are considered more fully under 
the chapter on potash salts. 

1 Bui. Expt. Sta., Tokyo, 1, No. 1 (1905) ; cited from Loew. 



CHAPTER XXIII 

SODIUM SALTS 

Sodium is present in the air. as sodium chlorid, in the 
shape of fine powder. This is derived chiefly from the 
winds which sweep into the air the spray of the ocean and 
of salt lakes. The winds also carry into the air salt dust 
of terrestrial origin. The quantity of common salt thus 




Full ration Full ration One-fourth ration Full ration 

sodium carbonate potassium carbonate sodium carbonate, sodium carbonate. 

One-fourth ration One-fourth ration 

potassium carbonate potassium carbonate 

Fig. 56. — Mangels, Limed. 

Fertilized alike with phosphoric acid and nitrogen. 

carried inland is sufficient to materially raise the chlorin 
content of spring and well waters in near proximity to the 
sea coast. 

In addition to this atmospheric source of sodium, it is 
a prominent constituent of many important and widely 
distributed minerals and rocks. 

486. Mineral sources of sodium salts. — Orthoclase, 
one of the chief minerals of certain granites, frequently 
contains from 2 to 6 per cent of soda ; oligoclase, also often 

333 



334 FERTILIZERS 

present in granite, contains 8 per cent of soda; diorite 
likewise contains 3 per cent of soda ; and certain volcanic 
rocks contain as much as 6 per cent. Thus these and other 
sodium-bearing minerals and rocks add, by their disin- 
tegration, to the soluble sodium salts of the soil, and hence 
aid in their distribution throughout all arable soils. It 
must be borne in mind, however, that in humid regions 
sodium as chlorid, and also in other combinations, is being 
continually leached way, whereas, on the contrary, in 
arid regions the soluble sodium salts often accumulate to 
such an extent as to inhibit plant growth, or at least the 
growth of the usual agricultural plants. 

487. Black alkali. — Chief among the noxious so- 
dium salts is the so-called " black alkali " (sodium car- 
bonate, Na 2 C0 3 ), which was so named because of the 
dark color imparted to the otherwise white sodium car- 
bonate, by vegetable decomposition products which it 
dissolves. 

488. Quantities of common salt injurious to crops. — 
The soluble sodium of soils is present chiefly as chlorid, 
although it may occur as nitrate, sulfate, carbonate, or 
silicate. In dry soils quantities of sodium chlorid as great 
as 1 to 1000 parts of soil are likely to be injurious to 
plants, though in very wet soils nearly twice that quantity 
may be endured. 

489. The presence of soda in plants. — The presence of 
soda seems to be practically universal in cultivated plants, 
though the amounts in different plants vary widely accord- 
ing to the nature of the plant and to the condition under 
which it is grown. There is also a wide variation in the 
percentages present in different parts of the same plant. 
In elevated regions, very remote from the sea, the quan- 
tity of soda present in plants is so small that cattle reared 



SODIUM SALTS 



335 



there require much more common salt than those fed on 
plants grown nearer the sea. 

According to Pagnoul, 1 Peligot first pointed out the 
difference in the action of soda and of potash upon plants. 
He made analyses of many varieties of plants, 2 and claimed 
that the ash of most plants, including spinach, contained 
no soda, although he found it in fodder beets and in species 
of Atriplex and Chenopodium. When, later, Bunge 3 
called attention to the faulty method of analysis by which 
much or all of the soda might have been lost, Peligot re- 




Full ration 
common salt 



Full ration 
muriate of potash 



One-fourth ration 

common salt. 
One-fourth ration 
muriate of potash 



Full ration 

common salt. 

One-fourth ration 

muriate of potash 



Fig. 57. — Mangels, Limed. 
Fertilized alike with phosphoric acid and nitrogen. 



peated some of his earlier work, 4 taking special precautions 
against the loss of soda, and again found soda absent 
from certain plants. 

It was found by Deherain 5 and Sjollema 6 that potato 
tubers were free from soda, notwithstanding that sodium 

1 Ann. Agron. (1899), 467. 

2 Compt. rend. (Paris), 2 (1867), 729 ; and in later issues of the same 
journal. 

3 Annal. de Chemie et Pharm., 172, 16. 

4 Compt. rend. (Paris), 76 (1873), 113 ; Abs. Centralb. f. Agr. Chem., 
4 (1873), 222-226. 

6 Ann. Agron., 9 (1883), 511. 
« Jour. f. Landw. (1899), 309. 



336 FERTILIZERS 

salts were present in the manures. It is reported by 
Pagnoul l likewise that potatoes grown in soil which con- 
tained soda were themselves free from it, and later he 
asserted 2 that sodium may be absent if large amounts of 
potash are used in the manures. He found, however, 
that oats absorbed soda if there was a deficiency of potash 
in the manures and fertilizers. 

That the use of sodium salts in the manures may in- 
crease the quantity of it in some plants is shown by Zoller, 
who found in the stems of beans 5.1 per cent when soda 
was so employed, but only 1.36 per cent when it was not. 
Similar wide variations were found by Wheeler and Hart- 
well 3 in various crops. 

It is reported that Coutejean and Guitteau 4 determined 
the potash and soda percentages in over six hundred 
varieties of plants, and large numbers of similar deter- 
minations are given by Wolff. 5 It appears that the soda 
content of plants may therefore vary from mere traces 
to high percentages. The amount found by Hilgard 6 in 
the ash of greasewood (Sarcobattus vermiculatus) was 40 
per cent. 

490. Sodium salts as indirect manures. — It was found 
by Birner and Lucanus 7 that the application of sodium 
sulfate favored the passage of phosphoric acid into the 
plant and that it lowered at the same time the percentage 
of lime. Upon applying potassium chlorid, the ash and 

1 Compt. rend. (Paris), 80 (1875), 1010; Abs. Jahresb. f. Agr. Chem., 
18, 259. 

2 Ann. Agron., 20 (1894), 467-479. 

3 An. Rpt., R. I. Agr. Expt. Sta., 19 (1905-1906), 235-251. 

4 Compt. rend. (Paris), 86 (1878), 1151-1153; Abs. Centralb. f. Agr. 
Chem. (1879), 259. 

6 Aschen-Analysen. 

6 Jahresb. f. Agr. Chem. (1892), 183. 

'Landw. Vers.-Sta., 8 (1866), 140. 



SODIUM SALTS 337 

dry matter of the plants were enriched in magnesia and 
potash, but became poorer in lime, sulfuric acid, and phos- 
phoric acid; and upon applying sodium chlorid a still 
more striking change in the same direction ensued. On 
the other hand, Storer x cites Dyer as authority for the 
statement that common salt seems to be needed to bring 
out the action of phosphates and nitrates, yet from ob- 
servations by various experimenters it would appear that 
there are many conditions under which common salt is 




Full ration Full ration One-fourth ration Full ration 

sodium carbonate potassium carbonate sodium carbonate, sodium carbonate . 

One-fourth ration One-fourth ration 

potassium carbonate potassium carbonate 

Fig. 58. — Flat Turnips, Limed. 

Fertilized alike with phosphoric acid and nitrogen. 



used to check the too rapid formation or assimilation of 
nitrates. It is apparent, therefore, that the effect produced 
hinges upon the peculiar conditions which exist in any 
given case. 

It has been shown by various experimenters that upon 
applying calcium salts to ordinary soils, considerable 
amounts of potash are often rendered soluble, and the 
high efficiency of sodium chlorid in this respect, under 
exaggerated conditions, has been shown by Passarini. 2 
Nevertheless, Muntz and Girard hold that if sodium chlorid 

1 Agriculture, II (1897), 595. 

2 Quorta Seine 17, Dist. la~2a; 72, della Raccolta Generate, 15. 

z 



338 FERTILIZERS 

exerts a solvent action upon soil phosphates or upon soil 
silicates, containing potash, it must be extremely limited. 
It must, however, be evident that rich potash-bearing 
zeolites or, possibly, glauconite would be likely to yield 
more potash than would be freed from feldspars ; and they 
would also yield considerably greater quantities of potash, 
if rich in that ingredient, than if they were poor in potash 
at the outset and were already rich in soda, lime, and 
magnesia. 

In the course of experiments with sodium chlorid and 
with sodium carbonate, at the experiment station of 
the Rhode Island State College, the serious deficiency of 
potash which soon developed, in a silt loam soil of granitic 
origin, indicated, if there had been a liberation of potash 
from zeolitic or other silicate combinations, that it could 
neither have been of very great consequence at the outset 
nor of long duration. In this case generous amounts of 
readily available phosphoric acid, as well as occasional 
applications in less available form, were made throughout 
the course of the experiments, hence it was not a question 
of liberation of native phosphorus compounds of the 
soil. Under the circumstances which existed, it was 
found that on both lightly and moderately limed soil, both 
sodium compounds showed an unmistakable tendency, in 
two or three different years and with several different crops, 
to increase the percentage of phosphorus in the dry matter 
of the plants. 1 

491. Concerning the benefit to crops from applying 
sodium salts. — The old and modern writers on agricul- 
tural chemistry and on general agriculture agree that 
marked benefit to farm crops often follows the application 
of sodium salts, though reference is commonly made to 

'An. Rpt., R. I. Agr. Expt. Sta., 19 (1905-1906), 194-219. 



SODIUM SALTS 



339 



sodium chlorid. Recently Smets and Schreiber x have 
pointed out that sodium salts are highly beneficial to 
certain plants under given conditions of field culture. 
Frequent ill effects from such use of sodium chlorid are 
nevertheless on record. 

It is apparent that sodium salts act more beneficially 
with some classes of plants than with others. From this 
it must be inferred that the different plants require unlike 
amounts of potash, which soda can liberate, that they are 




Full ration 
muriate of potash 



One-fourth ration 

common salt. 

One-fourth ration 

muriate of potash 



Full ration 

common salt. 

One-fourth ration 

muriate of potash 



Fig. 59. — Flat Turnips, Limed. 
Fertilized alike with phosphoric acid and nitrogen. 

unequally affected by such biological and physical changes 
in the soil as the use of soda may cause, or one is led to 
conclude that soda probably performs functions of direct 
physiological importance. 

The general recognition in Great Britain of the benefit 
from the application of common salt to soils is evident from 
the statement by Griffiths 2 to the effect that 250,000 tons 
of finely crushed common salt are used annually for ma- 
nurial purposes in the United Kingdom. 

In soils which contain calcium carbonate, it is possible 

1 Recherches sur les Engrais Potassiques et Sodiques, Maaseyck 
(1896). 

2 A Treatise on Manures (1889), 256. 



340 FERTILIZERS 

that common salt, by its reaction with sodium chlorid, 
may give rise to sodium bicarbonate, which, being more 
basic than the carbonate of lime, may affect the chemical 
reaction of the soil either favorably or unfavorably ac- 
cording to the variety of plant involved. It has even been 
asserted that it may, by its solvent action, render certain 
humous bodies of the soil either directly assimilable by 
plants, or else aid in the more rapid change of some of 
their constituents into other available forms of plant food 
ingredients. It was found by Prianischnikov, 1 when 
using sodium nitrate as a source of nitrogen in the growth 
of plants, that the medium in which they grew became 
alkaline by virtue of the sodium carbonate which resulted 
after the removal and utilization of the nitric acid by the 
plants. Indeed, this is in full accord with later observation 
of others and with the earlier classification of sodium nitrate, 
by Adolf Mayer, as a physiologically alkaline fertilizer. 

492. The effect of sodium salts dependent on various 
conditions. — That an excess of sodium carbonate in soils 
may be injurious, is well attested by the evil effect of the 
" black alkali " (sodium carbonate) of the arid and semi- 
arid regions of Canada, the western part of the United 
States, and elsewhere. If sodium chlorid is used on an 
acid soil, practically devoid of carbonates of lime and mag- 
nesia, it may aggravate the existing condition by ulti- 
mately increasing the acidity, whereas on a soil where the 
sodium chlorid can react with carbonate of lime to form 
sodium bicarbonate, the reverse effect might follow. 

493. The influence of sodium salts on the conservation 
and movement of soil moisture. — It has been shown by 
Ricome 2 in experiments with Malcolinia maritima and 

1 Chem. Ztg., 66 (1900), 701. 

2 Compt. rend., 137 (Paris, 1903), 141 ; Abs. Centralb. f. Agr. Chem., 
33 (1904), 224. 



SODIUM SALTS 



341 



Alyssum maratinum that the presence of sodium chlorid 
in the solution outside of the plant may lessen the quantity 
of water absorbed, and thus protect it from an injurious 
degree of transpiration. The presence of the sodium salt 
in the plant itself was without beneficial effect in this 
connection, unless the existing conditions were also such 
as to permit of easier absorption. 

Since soluble salts, such as sodium chlorid, increase the 
surface tension of liquids, it has been pointed out by King 
that they may be helpful by facilitating the movement of 




Full ration 
common salt 



Full ration 
muriate of potash 



One-fourth ration 

common salt. 
One-fourth ration 
muriate of potash 



Full ration 

common salt. 

One-fourth ration 

muriate of potash 



Fig. 60. — Chicory, Limed. 
Fertilized alike with phosphoric acid and nitrogen. 

the soil water towards the surface, and hence towards 
the plant roots. 

In certain soils sodium chlorid exerts a beneficial floc- 
culating influence, yet in others in which the bicarbonate 
is readily formed, it may have the opposite effect. 

It is generally held by farmers that common salt added 
to a soil helps it to retain moisture, on which account it is 
helpful on light sandy soils which are readily subject to 
drought. This view is supported by the fact l that the 
presence of salts in the soil solution lessens evaporation 
from the surface so long as they remain in solution, and 

1 King, A Textbook of the Physics of Agriculture (1901), 106. 



342 FERTILIZERS 

in case they are separated at the surface, they then even 
serve the purpose of a mulch. 

494. The effect of sodium salts upon osmotic pressure. 
— There appears to be evidence that conditions may arise 
in which sodium salts, or other soluble salts, may be of 
service in connection with the growth of plants in solu- 
tions, merely by their increase of the osmotic pressure, 
though whether this would have any bearing upon the 
growth of plants in a normal way in soils is problematical. 

495. The possible physiological and manurial functions 
of sodium salts. — Some writers attribute to potassium 
but the one function of aiding in the formation and trans- 
location of starch, though Benecke 1 indicates others, for 
in discussing sodium he suggests its osmotic service to the 
plant as a substitute for potassium. As concerns potas- 
sium salts, in this connection, Copeland 2 has asserted that 
they are direct or indirect factors in maintaining turgor, 
also that upon the omission of salts containing phosphorus, 
magnesium, or sulfur, the plants, though showing poor 
growth, exhibited high turgor, whereas in the absence of 
potassium salts, the turgor was decreased and the growth 
stunted. Nevertheless, Pfeffer 3 holds that turgor is a 
result of conditions of growth rather than a cause of it; 
a view which seems to have the greater support. 

It is held by Pfeffer that phosphorus may be as essential 
as potassium in effecting the formation and translocation 
of starch ; and as sodium often aids in carrying phosphorus 
to the plant, it may thus render an indirect service. 

It has indeed been suggested by Goodale 4 that sodium 

x Ber. deut. bot. Gesell., 12 (1894), Gen. Vers., 114; quoted from 
Copeland. 

2 Bot. Gazette, 24 (1897), 411. 

» The Physiology of Plants (translated by Ewart) (1900), 1, 141, 

4 Physiological Botany (1885), 255. 



SODIUM SALTS 



343 



may be substituted for a portion of the potassium required 
by the plant. 

Owing to the large quantities of sodium in certain plants, 
A. Mayer thinks that it may perhaps be essential or at 
least serviceable to them. 




Fig. 61. — Onions. 
With full ration of common salt. Fertilized liber- 
ally with nitrogen and phosphoric acid and limed. 
In these respects like Figs. 62 and 63. 

Attention has also been called by Mayer to the free 
movement of the salts of sodium within the plant, and he 
suggests that soda may just as well combine with organic 
acids in the plant as to have this service performed by 
some other base, and yet this would be without necessary 



344 FERTILIZERS 

physiological significance. In this connection an experi- 
ment by Mercadante is of interest, for upon growing 
species of Oxalis and Rumex, without potassium, neither 
fruit nor flower formed, and but one-eighth the normal 
amount of acid was present. The oxalic and tartaric 
acids produced were found combined with lime, and but 
little starch or sugar was formed. 

Under normal conditions, therefore, some of the organic 
acids, formed during the synthesis of the proteins, are 
found combined with potassium. This suggests that not 
only potassium, but also sodium, if there is a partial lack 
of the former, may perform a highly useful function as a 
neutralizer of organic acids, and, as Mayer has suggested, 
it may act as a soluble conveyor of at least oxalic acid 
to other parts of the plant, where by contact with lime the 
acid is precipitated as insoluble calcium oxalate. As a re- 
sult the acid is prevented from reaching toxic propor- 
tions in certain vital parts of the plant. 

It was held by Salm-Horstmar 1 as early as 1856 that 
sodium was essential to wheat and oats, in connection with 
the perfection of the seed. 

From water-culture experiments with Indian corn, 
Stohmann 2 concluded that sodium was essential to its 
perfect development. It has been suggested by Miintz 
and Girard that if sodium is essential, the mangel wurzel 
is a plant most likely to require it. Sodium is mentioned 
also by Aikman, Johnson, and others, as possibly essential 
to plants ; but if so only in very minute quantities. 

496. Results by Jordan and Genter. — It was con- 
cluded by Jordan and Genter 3 that " soda cannot re- 

1 Versuche und Resultate iiber die Nahrung d. Pflanze, 12, 27, 29, 
and 36. 

2 Flora (1890), 207-261. 

8 Bui. 192, N. Y. (Geneva) Agr. Expt. Sta., December, 1900. 



SODIUM SALTS 345 

place potash as an active agent in the development of 
plant life," or, in other words, that it could not replace it 
in function though taking the place of some of it in the 
quantity found within the plant. 

497. Soda in connection with diastatic action. — An 
interesting suggestion as to a possible independent phys- 
iological function of soda in plants has been made by 
Suzuki * in which he recalls the work of Chittenden, show- 
ing that the efficiency of vegetable diastase is heightened 
by small quantities of sodium chlorid (0.24 per cent). 
The same has been shown by Wachsmann 2 to be the case 
with animal diastase; furthermore it has been observed 
by A. Mayer that a 1 per cent solution of potassium chlorid 
not only retarded diastatic action, but that smaller amounts 
exerted no decisive effect. In consequence he concludes 
that sodium chlorid may act indirectly, in conjunction 
with the diastase, in the transportation of starch to the 
growing tips of plants. 

498. Atterberg's experiments with soda. — An experi- 
ment is on record by Atterberg 3 in which plants were 
grown in quartz sand in which, in one series, calcium salts, 
and in another, sodium salts, were substituted for a part 
of the potassium, with the result that the yields fell off in 
the former case far more than in the latter. It has, how- 
ever, been learned by correspondence that it was ascer- 
tained later that the particular lot of sand which was used 
in the experiments contained surprisingly large quantities 
of sodium chlorid, and hence it may also have contained 
some potassium salts capable of being liberated by sodium 
salts in a greater degree than by the action of lime. This, 

1 Bui. Col. of Agr., Tokyo, Imp. Univ., 6 (1905), No. 4, 408. 
2 Pfiuger's Archiv, 91 (1902), 191. 
3 Deut. landw. Presse (1891), 1035. 



346 



FERTILIZERS 



therefore, throws some doubt upon whether the benefit 
was a direct one or was wholly or in part indirect, by virtue 
of the liberation of potash. The following year Wagner 
and Dorsch x called attention to the manurial value of 
sodium salts, asserting that, in case potash was lacking, 
sodium was capable, in connection with certain plants, of 



iS^?iiP^*k? 


?>'• *£mjtf&&m^' r €d 




*^0W 




^2 * 


- ~ : -• -" 






Ws^^[* 




$§£« 






«5$ 






., » , ? 





Fig. 62. — Onions with Muriate or Potash. 

Full ration of muriate of potash. Fertilized lib- 
erally with nitrogen and phosphoric acid s and limed. 
In these respects like Figs. 61 and 63. 

increasing the crop as much as one-half. Still later Stahl- 
Schroeder published certain researches which seemed to 
him to contradict the idea that the sodium in the experi- 
ments by Atterberg and by Wagner and Dorsch had ex- 
erted a direct effect, but rather that it was indirect by 
virtue of the liberation of potassium. 

499. The experiments at Bernburg. — In a series of 

1 Die Stickstoffdiingung d. landw. Pflanzen (1892), 227-242. 



SODIUM SALTS 347 

experiments by Hellriegel, Wilfarth, and others, 1 at Bern- 
burg, Germany, made in quartz sand or in mixtures of 
sand and peat, extracted previously in order to remove 
practically all of the available potassium, it was found 
that there was an increase in crops of barley and oats, 
when a deficiency of potash in the manures was partially 
made up by additions of sodium salts. There were in- 
dications, nevertheless, that buckwheat, potatoes, and 
perhaps other crops may not be benefited by sodium 
compounds. 

In discussing the work of Hellriegel and Wilfarth, 
Schneidewind 2 calls attention to the fact that they were 
able, by substituting some soda for a part of the potash in 
the fertilizers, to produce the same amounts of sugar and 
of total dry matter as with the use of more potash. The 
latter believed, nevertheless, that the good effect of soda, 
which he had also observed in connection with beets, 
was not due to physiological functions of the sodium 
salts, but to the fact that the solubility of the sodium 
nitrate, sodium phosphate, and sodium sulfate was 
greater than the solubility of the corresponding potassium 
salts; and that on this account the several plant foods 
when in combination with sodium were more available. 
This latter conclusion is, however, open to serious 
question in view of the fact that Hellriegel and Wilfarth 
worked in pots which were watered artificially in order that 
optimum amounts of water might at all times be main- 
tained in the soil; furthermore, under ordinary soil con- 
ditions plants are known to make use, in a satisfactory 
manner, of the various potassium salts. 

It has been pointed out by Hartwell and Pember 3 

1 Arbeiten Deut. landw. Gesell., Hefts 34 and 38. 

2 Jour. f. Landw. (1898), 7, 8. 

3 An. Rpt., R. I. Agr. Expt. Sta., 21, 249, 250. 



348 FERTILIZERS 

that in the experiments by Hellriegel and Wilfarth, when 
sodium was added, more potassium was removed in the 
crop than otherwise ; and, furthermore, that the increase 
in growth was no more than might have been expected 
from the extra potassium thus rendered available. It 
was assumed by the latter investigators that when the 
sodium salts were deficient in the soil-culture medium, some 
of the potash applied in the fertilizers was fixed by the 
silica or otherwise, in such form that all of it could not 
be readily secured by the plants, but that a part of the 
potassium thus fixed was rendered available to a greater 
degree upon the addition of sodium salts. 

500. The Rhode Island experiments. — It was on 
account of the many conflicting ideas as to the possible 
functional benefit of sodium salts that the matter has been 
studied exhaustively at the experiment station of the 
Rhode Island State College. At first, plants were grown 
in the field, in which case great benefit from common salt 
and from sodium carbonate resulted, when employed in 
connection with small applications respectively of muriate 
of potash and of potassium carbonate. In fact, even 
in cases where more than 300 pounds of muriate of potash, 
or its equivalent of potassium carbonate, were employed, 
the yields of mangel wurzels were doubled by sodium salts. 
In all cases heavy applications of organic nitrogen (chiefly 
in dried blood) and of available phosphates were made, 
in order to eliminate, in so far as possible, any effect of 
the sodium salts by way of rendering nitrogen and phos- 
phoric acid available to the plants. In the course of this 
work many different kinds of plants were analyzed in 
order to determine the influence of the soda upon the 
composition of the mineral matter : and, in some cases, 
1 An. Rpt., R. I. Agr. Expt. Sta., 19, 186-316. 



SODIUM SALTS 



349 



upon the organic constituents of the plants. This work 
indicated that benefit from soda seemed to have resulted, 
in certain cases, which could not be readily explained 
upon the assumption that it was due to a greater liberation 
of potash. In order, however, to further remove doubt 



r'~*?£. •_ v3s3 


8E* -v 1 


< 'S&JjP 


k. " -7 .JlKt ^mmrri 


■%>*,■ ■"• \, *--* 




- 

ir?i^3wr^fti^ '-£ 'M^' -■'■„•?' '•' ■' 
Mf&vTtr-' — -."■■< ...-■ — 




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Fig. 63. — Onions. 
FmZZ ration of common salt and full ration of mu- 
riate of potash. Fertilized liberally with nitrogen 
and phosphoric acid, and limed. In these respects 
like Figs. 61 and 62. 

on this point, an extensive series of water-culture experi- 
ments was made at the Rhode Island station by Wheeler, 
Hartwell, and Pember, 1 and by Braezeale, under condi- 
tions where indirect manurial action was impossible. 
Precautions were also taken to eliminate the possibility 
of benefit from the sodium salts being due to a change in 

i An. Rpt., R. I. Agr. Expt. Sta., 20 (1906-1907), 299-357 ; An. Rpt., 
21 (1907-1908), 243-285. 



350 FERTILIZERS 

the relation of the nutrients, to the chemical reaction, to 
the concentration of the solution, or to other similar 
effects, rather than to some physiological function of the 
sodium salt. As a result it appeared that though possibly- 
unable to wholly replace potash in any one function, or 
at least in all of its functions, in connection with the 
growth of certain plants, sodium may and often does 
perform some part of one or more of the important func- 
tions of potassium, and thus increase the amount of dry 
matter which the plant can produce. 

501. The practical significance of soda in agriculture. — 
The most practical feature connected with the utilization 
of sodium salts is to use for the growing of mangels, 
radishes, turnips, and such other crops as can make good 
use of them, fertilizers like nitrate of soda and kainit, 
which furnish nitrogen and potash ; and at the same time, 
without added cost, supply soda. The soda, in such cases, 
serves as an insurance against a possible shortage of 
potash and may materially add to the yields. 



CHAPTER XXIV 

IRON AND MANGANESE 

The importance of iron to plants has long been known, 
and now new interest attaches to manganese. 

502. Iron in its relation to plant growth. — Experi- 
ments have shown that a lack of iron in plants causes 
pathological chlorosis, and it is believed that it may- 
affect the protoplasmic structure in which the chlorophyl 
is deposited. It is therefore vital to the higher plants. 

The necessity of iron may be readily shown by growing 
Indian corn or other plants for some time in a nutritive 
solution, which is complete excepting for the omission of 
iron. After having reached an advanced stage of chlorosis, 
the condition can still be remedied in a very short time by 
the addition of ferric chlorid to the nutrient solution. 

Sufficient iron is present in practically all soils to meet 
the ordinary needs of plants. It has, nevertheless, been 
asserted that certain soils of northern Michigan are so 
deficient in this element that the plants grown upon them 
do not furnish sufficient iron to the cattle of the region to 
permit of their being brought successfully to maturity. 
It is stated that this can be accomplished, nevertheless, 
if they are supplied with fodder brought from elsewhere, 
or if they are removed after a time to some other section 
of the state. 

Certain salts of iron may be reduced to lower oxid com- 
binations under anaerobic soil conditions, or the lower 

351 



352 FERTILIZERS 

combinations may be oxidized upon draining the land or 
in times of drought. This latter change accounts for the 
frequent transformation from a bluish to a reddish brown 
tint observed in soils when, upon their exposure to the air, 
iron carbonate is oxidized to hydrous sesquioxid of iron. 
Where, as in muck and peat soils, the conditions are at 
times only partially favorable to oxidation, toxic organic 
compounds of the lower oxid of iron are said to result. 
In better aerated bogs, also, toxic iron protosulfate (FeS0 4 
+ Aq.) may be formed by the oxidation of iron sulfid 
(FeS 2 ), provided the latter is present in the sands or 
gravels frequently used as a covering for the surface. 
In the latter case the toxicity can be counteracted by lim- 
ing, whereupon the iron salt is broken up to form gypsum, 
and the iron is further oxidized. Similar, but usually less 
striking, effects may also be noted in wet uplands. 

503. Manganese in plants and soils. — It has been 
said that the existence of manganese in plants was first 
pointed out by Scheele, who found it in the ash of wild 
anise and of certain kinds of woods. It was later noted by 
Herapoth in the ash of the radish, beet, and carrot and by 
Salm-Horstmar in oats. 

In 1872 Le Clerc recognized manganese as almost 
universally present in soils and plants, although present 
in the former usually in quantities much below 1 per cent. 

504. Manganese as a fertilizer. — It was found by 
Giglioli that manganese dioxid increased the yields of both 
corn and wheat. 

Experiments by Fukutome l have shown that the em- 
ployment of ferrous sulfate, in conjunction with manganese 
chlorid, was very helpful to flax, whereas either employed 
without the other had but little effect. In experiments by 

1 Bui. Col. of Agr., Tokyo, 6 (1904-1905), 137. 



IRON AND MANGANESE 353 

Garola, also with flax, it was found that the employment 
of salts of manganese in the manures not only increased 
the growth, but also the assimilation of nitrates, phos- 
phorus, potassium, calcium, and other ingredients. 

Soils that were " oat-sick " were restored by Sjollema 
and Hudig to a normal condition upon the employment of 
manganese sulfate. 

The amounts of manganese which may be safely and 
often profitably applied per acre, range, according to 
various experimenters, from nine to thirty-six pounds per 
acre. It is recommended that the salts be pulverized and 
mixed with the chemical fertilizers which are employed, 
or that they be mixed with the stable manure before it is 
applied to the land. 

505. The manganese in Hawaiian soils. — Recent 
examinations of certain black Hawaiian soils have shown 
that they contain from about 4 per cent to nearly 10 per 
cent of manganese oxid (Mn 3 4 ), whereas the red soils of 
Hawaii show a range of from only 0.15 to 0.37 per cent. 

506. Plants unlike in endurance of manganese. — It 
appears that agricultural plants are very unlike in their 
relation to manganese, for the quantity present in the 
black Hawaiian soils, although not enough to interfere 
with the successful growth of sugar cane, is so toxic to 
pineapples that the plants often fail to bear fruit. Like- 
wise Aso l found rice more resistant than either barley or 
wheat to salts of manganese, and he has also shown that 
its ill effects are worse in cold than in warm weather. 

507. Variations in the manganese content of plants. — 
Manganese is very commonly present in the ash of plants, 
and Kelley 2 reports that the content of Mn 3 4 found 

1 Bui. Col. of Agr., Tokyo, Imp. Univ., 5, 177-185. 

2 The Jour, of Ind. and Eng. Chem., 1 (1909), 536. 
2a 



354 FERTILIZERS 

in the ash of pineapple leaves varied from 1.65 to 2.12 
per cent, which he considers low in view of the high man- 
ganese content of the soil upon which they were grown. 
In the ash of the bark and leaves of the Norway spruce, 
Schroeder found 35.5 and 41.2 per cent, respectively, of 
Mn 3 4 . The fact that so little manganese is found 
in some plants has led to the suggestion that possibly at 
certain stages of the growth of the plant it may pass back 
into the soil through the roots, or that it may be excreted 
from the aerial portions of the plants, as has been shown 
to be the case with certain other mineral plant constituents. 

508. The effect of manganese on enzymes. — It was 
shown by Bertrand l many years ago that much manganese 
is present in the ash of oxidizing enzymes and that certain 
soluble salts of manganese increase the power to carry 
oxygen. In consequence, he suggested its practical trial 
by making application of it to the soil. 

The beneficial results from the use of manganese are 
supported also by the experiments of Loew and Sawa. 
The latter investigators found that manganese sulfate, 
in moderate quantities, was toxic to barley. It exerted 
a bleaching action upon the chlorophyl, and increased 
the intensity of the oxidase and peroxidase reactions. 

509. Manganese increases many crops. — When used 
in very dilute solutions, manganese sulfate was found by 
Loew and Sawa to promote the development of the plants. 2 
The same was found by Aso to be true of rice ; and Na- 
gaoka 3 reports an increase of 37 per cent in rice, upon the 
application of 13.7 pounds of manganese sulfate per acre 
(77 kilos per hectare). A similar result is reported by 

i Compt. rend. (Paris), 124, 1032. 

2 Bui. Col. Agr., Tokyo, Imp. Univ., 5, 172. 

3 Ibid., 6, No. 1. 



IBON AND MANGANESE 355 

Voelcker from Woburn (England) in experiments with 
wheat and other crops. In experiments by Sutherst 1 
it was found that small amounts of manganese compounds, 
including the dioxid, were helpful to maize, yet he states 
that Salamone found large amounts injurious. 

It has been shown by A. Anduard and P. Anduard that 
the employment of manganese increased the yields of 
wheat and of kidney beans, but lessened slightly the yields 
of carrots and of potatoes. 

510. Roots change the oxidation of manganese. — In 
view of the alleged oxidizing power of plant roots, which 
it is asserted is even stimulated by salts of manganese, it 
is of interest to note that Kelley found the soil darker 
immediately about the roots of unhealthy pineapple 
plants than elsewhere, and that Aso discovered man- 
ganese dioxid adhering to the roots of wheat grown in 
solutions containing manganese sulfate, thus showing that 
the roots effect a change in the oxidation of the manga- 
nese. It is, however, claimed by Schreiner and Sullivan 2 
that the beneficial effect of manganese is due to its pro- 
moting oxidation; they assert, however, that "the re- 
lation between oxidation and catalysis is not as clear as 
it should be, even in the plant where it has been exten- 
sively studied." It is evident in any event that manga- 
nese, if employed for its alleged " catalytic," "stimulating," 
or " oxidizing " effect, must be used very cautiously, es- 
pecially if the degree of sensitiveness of the particular 
plant under experiment is not known at the outset. 

511. Manganese may aid chlorophyl development. — 
In growing plants by way of water-culture, it has been 
found that if iron is slightly deficient, the addition of a 

1 The Transvaal Agr. Jour., 6, No. 23. 

2 Bureau of Soils, Bui. 73, U. S. Dept. of Agr. (1910). 



356 FERTILIZERS 

soluble manganese salt causes chlorophyl development 
and the renewed vigor that would be expected in such a 
case ; yet, as was pointed out by Sachs l and later by 
Loew and Sawa, iron cannot be fully replaced by manga- 
nese in the production of chlorophyl. 

A very full review of the experiments thus far conducted 
with manganese is given by Giglioli and Rousset, 2 and 
brief reference to much of the work is also made by 
Schreiner and Sullivan (I. c.) and others. 

1 Hoffmeister, Handbuch Phys. Botanik, 4 (1865), 144; cited from 
Schreiner and Sullivan. 

2 Ann. Sci. Agron., 2 (1909), 81. 



CHAPTER XXV 

CHLORIN, SULFUR, SILICA, CARBON DISULFID, TOLUENE, 
AND OTHER MISCELLANEOUS SUBSTANCES 

Many miscellaneous substances including iodin, bromin, 
boron, lithium, and others have been tested as to their 
influence on plant growth, but only the more important 
of these are considered in this chapter. 

512. Chlorin. — Whereas there have been some in- 
stances in which chlorin has seemed to be slightly bene- 
ficial to plant growth, especially in connection with buck- 
wheat, potatoes, and possibly other plants, through some 
indirect action not definitely determined, it is nevertheless 
considered as a non-essential element. For this reason 
it is not classed as a plant food. 

513. Sulfur. — Sulfur is essential to plant growth, and it 
is required in considerable amounts in the formation of 
certain essential oils, like those of the horseradish, cress, 
and for the proteins, which are present in all plants. It 
is, nevertheless, one of the elements supposed to be sel- 
dom, if ever, so deficient in soils as to require that it be 
supplied artificially. This is more especially the case in 
regions where the extended use of ready-mixed commercial 
fertilizers is common, since they usually contain consider- 
able quantities of gypsum as one of the ingredients, not 
only of ordinary superphosphates, but also of certain of 
the German potash salts. Sulfur is also added to soils 
in potassium sulfate, in the low and high grade sulfates of 

357 



358 FERTILIZERS 

potash, and likewise in the protein compounds of nitroge- 
nous organic fertilizing materials. 

514. Sulfur may become depleted in soils. — It has 
been shown by Hart and Peterson that where farm-yard 
manure is applied to soils regularly and in reasonable quan- 
tities, the original quantity of sulfur in the soil is maintained 
or even increased. Soils, on the contrary, which have been 
cropped for from fifty to sixty years, and which have re- 
ceived but little manuring, were found to have lost 40 per 
cent of their original sulfur, as indicated by comparisons 
with similar virgin soils. 

It has been further pointed out by Hart and Peterson 
that many crops remove sulfur from the soil in much 
greater quantities than those usually given in the tables 
of analyses of farm crops. This fact, however, may merely 
signify that a great excess of sulfur is present in the soil 
in assimilable form, and hence the results may serve as a 
more effective argument against its lack than for the ne- 
cessity of its application. 

515. The relation of sulfur and phosphorus in plants 
and soils. — The fact has also been pointed out by Hart 
and Peterson that the amount of sulfur trioxid represented 
in average crops of the grain and straw of cereals is about 
two-thirds as great as the amount of phosphoric acid which 
these crops remove ; that in mixed meadow hay the quan- 
tities of the two are about equal ; and in certain legumes the 
amount of sulfur trioxid represented may approach, and 
in alfalfa even exceed, the amount of the phosphoric acid. 

An average crop of cabbage is said to remove from the 
soil the equivalent of 100 pounds per acre of sulfur trioxid, 
and in normal soils the amount in an acre-foot of soil was 
found by the method of fusion with sodium peroxid to be 
only from 1000 to 3000 pounds. 



CHL0R1N AND OTHER SUBSTANCES 359 

The annual addition to the soil of sulfur trioxid in the 
rainfall, as estimated by Hart and Peterson, for Madison, 
Wisconsin, is said to be from 15 to 20 pounds per acre, 
whereas the estimated losses by leaching, based upon the 
yearly drainage from the Rothamsted (England) experi- 
mental fields, are assumed to be about 50 pounds per 
annum. 

516. Need of sulfur may need investigating. — In 
view of the preceding, and other facts, and of the attention 
called by Bogdanov, 1 as well as by Dymond, Hughes, and 
Dupe 2 to the possible importance of the sulfur question, 
Hart and Peterson believe that the possible need of an 
artificial supply of sulfur should be given due considera- 
tion in connection with future researches involving soils 
and fertilizers. 

517. Silica in plants. — Silica is an important con- 
stituent of the ash of the grasses and rushes and also of 
many other plants. The ashes of some clovers, and of 
the straws of cereals, have been found to contain from 40 
to 70 per cent of silica. In fact, this plant silica, by virtue 
of its unusual solubility, may have some heretofore un- 
considered value in the soil, in connection with green 
manuring and with the use of stable manure and straw, 
by way of aiding in the formation of zeolitic double salts 
of lime, magnesia, and the alkalies, by which the absorp- 
tive capacity of light soils may be advantageously in- 
creased. 

518. Suggested functions in plants. — Silica has been 
supposed to serve as a protection and support in the cell 
walls, although not considered absolutely essential to plant 
growth. 

1 Abs. E. S. R., 11, 723. 

2 Jour. Agr. Sci., England, 1 (1905), 217. 



360 FERTILIZERS 

It has been asserted by Wolff that silica favors the mi- 
gration of phosphoric acid from maturing stems and leaves 
to the seeds which are in process of development ; for he 
secured a larger number of perfect grains in its presence 
than in its absence. Nevertheless, four generations of 
maize were grown by Jodin without silica, other than that 
derived from the dust of the air and from the vessels used 
in the experiment, but yet without apparent ill effect upon 
the plants. From what is now being learned about in- 
dividual plant peculiarities, it would, however, be unwise 
to conclude from experiments with maize as to the needs 
of all other higher plants. 

519. Silica may replace other ingredients in the " lux- 
ury " consumption. — In experiments with oat plants 
Wolff determined, in the presence of an abundance of all 
of the other essential elements, the minimum of each which 
was necessary, but found nevertheless that he could not 
grow plants containing only these minima of all of them. 
In other words, there seems to be required a certain 
excess of mineral matter beyond such calculated minima, 
a part of which/' luxury " need may be supplied by silica 
very much as sodium seems to answer a part of the general 
need for a soluble base when potash is present only to the 
extent of that minimum vital to plant growth. 

520. Silica deposition checks sap diffusion. — It has 
been suggested by Ritthausen that silica performs a useful 
function through its well-regulated and gradual deposition 
as a gelantinous mass in the walls of cells, by which the 
diffusion of sap is gradually suspended, especially in the 
lower leaves which gradually become unnecessary and 
ineffective. By this process, the chief portion of the plant 
food contained in such leaves, together with all of the sap, 
is ultimately diverted to the building up of new shoots 



CHLORIN AND OTHER SUBSTANCES 361 

and to parts of the plant which, in the later stages of growth, 
have become more important. 

521. Carbon disulfid often increases crops. — It was 
pointed out by A. Girard in 1894, in connection with ex- 
periments extending over a number of years, that highly 
beneficial effects upon the growth of plants followed ap- 
plications to the soil of carbon disulfid, which had been 
used at the rate of 2904 pounds 1 per acre for the destruc- 
tion of beet nematodes. The beet crop was ruined by the 
treatment, but the following year the wheat crop on the 
treated area was much better than elsewhere. Subse- 
quent experiments, in which carbon disulfid was used 
at the same rate, resulted in a gain of from 15 to 46 per 
cent in the yield of wheat grain, and of from 21 to 80 per 
cent in wheat straw. The yield of potatoes was similarly 
increased by from 5 to 38 per cent, and that of beets from 
18 to 29 per cent. The yield of clover was also increased 
by from 67 to 119 per cent. In the case of oats there was 
an increase in 1891 of 9 per cent in grain and of 30 per cent 
in straw. At Joinville, in 1892, oats showed a gain, from 
its use, of 100 per cent in grain and of 60 per cent in straw. 

522. Reasons suggested for the benefit to soils from 
using carbon disulfid. — For a long time much doubt 
existed as to the cause of the benefit which resulted from 
the use of the carbon disulfid. Among the suggestions 
offered in explanation was one to the effect that the ma- 
terial might have acted as a " stimulant," also that it 
might have aided by destroying certain " injurious sub- 
terranean insects " or " cryptogamic organisms," which 
might otherwise exert an injurious effect upon the roots 
of plants. This latter view was held by C. Oberlin, 2 an 

i Also E. S. R., 6 (1894-1895), 564, 565. 
2 Ibid., 565. 



362 FERTILIZERS 

Alsatian viticulturist who had made similar observations 
on vegetables, cereals, and forage crops. 

It was suggested by Milton Whitney that the effect of 
the carbon disulfid might be due to an alteration of the 
physical character of the soil. 

It had already been established by Warrington and was 
supported later by J. Perraud x that carbon disulfid checks 
excessive nitrification, but it was supposed that this was 
offset by benefit in other directions. 

Subsequent investigations made by P. Wagner led him 
to conclude that the preservative action of carbon di- 
sulfid on stable manure, and its beneficial action on soils, 
were probably due to its destruction of denitrifying or- 
ganisms. 2 

523. Treatment of soils with carbon disulfid costly. — 
The expense of the disulfid treatment at the time of the 
earlier experiments was very great. In fact, at the French 
price, 3^ cents per pound, it cost $96 per acre, and at the 
prevailing American prices, due to the high tariff and other 
causes, the cost of treatment was $290 per acre. The 
use of such costly' amounts of carbon disulfid simply for 
soil improvement was obviously not economical, but the 
experiments justified the belief that if but 175 to 290 
pounds per acre were employed, or such quantities as were 
customarily applied in vineyards, that some benefit would 
result aside from the mere destruction of the phylloxera. 

524. Carbon disulfid cures certain vetch clover and 
alfalfa " sick " soils. — Certain experiments by Oberlin 3 
have shown great benefit from the previous employment 
of carbon disulfid. He found that a soil made " alfalfa 

i Abs. E. S. R., 6 (1894-1905), 565. 

2 L'Engrais, 10 (1895), No. 18, 423; Abs. E. S. R., 7, 25. 

3 Jour. Agr. Prat., 59 (1895), 459-464, 499-503, 535-540. 



CRLOEIN AND OTHER SUBSTANCES 363 

sick "by the continuous growth of the crop for six years 
could be effectually cured by it, at least for a time. Sim- 
ilar results were secured also with hairy vetch and crimson 
clover. It is of interest to note that, among other queries, 
Oberlin raised the question if the treatment destroyed all 
soil organisms or only certain classes of them. 

525. Carbon disulfid not the only unusual compound 
to benefit soils. — It is impossible here to follow all of 
the developments in connection with sterilization by the 
heating of soils, likewise the use of carbon disulfid and 
all of the many other soil disinfectants, catalyzers, stimu- 
lants, indirect fertilizers, or whatever they may have been 
termed. Among these may be prominently mentioned 
toluene, tricresol, chloroform, zinc sulfate, and potassium 
permanganate. Most, or at least many of these com- 
pounds are too costly to permit of their general extensive 
application, even though they may be highly beneficial 
in certain special cases, and zinc compounds and certain 
other substances may, by their accumulation in the soil, 
become ultimately toxic. 

526. Disinfectants, like heating, destroy soil amebe. 
— Recently added interest has been lent to the subject of 
disinfecting soils by the observations of Loew l to the effect 
that soil " infusoria, flagellatae, and amcebe devour great 
numbers of microbes." This was soon- followed by the 
address of A. D. Hall 2 delivered at Sheffield, England, in 
1910, in which he called attention to the fact that Russell 
and Hutchinson of the Rothamsted laboratory had found 
that soils which had been subjected to sterilization by 
chemical treatment were found to contain exceptional 
amounts of ammonia, sufficient, in fact, to account for their 

i Science, 31 (1910), 988. 
*!&«*., 32 (1910), 363. 



364 FERTILIZERS 

subsequent increased fertility. It was further pointed 
out that the sterilization was not complete, yet at the out- 
set it greatly lessened the number of bacteria. This was, 
however, but temporary, for after the soil was watered and 
allowed to stand, it was discovered that they had increased 
far in excess of the normal numbers. A given Rothamsted 
soil, for example, containing normally seven million bac- 
teria per gram, contained but four hundred after heating ; 
yet a few days later the number present amounted to six 
millions and later reached forty millions per gram of 
soil. 

Toluene treatment. — Treatment of the soil with toluene 
resulted similarly, and the increase in ammonia in the soil 
was explained by the rapid multiplication of bacteria, a 
conclusion suggested by the fact that their increase was 
coincident with this gain. The nitrifying bacteria were 
eliminated by the treatment, and those remaining were of 
the ammonifying group. This work led to the idea that 
the treatment had destroyed something which had pre- 
viously limited the bacterial development, and upon fur- 
ther investigation it was found to have been the protozoa 
which fed upon the living bacteria. With the destruc- 
tion of these protozoa the ammonification of the organic 
matter in the soil progressed rapidly. The protozoa prob- 
ably concerned in the destruction of the bacteria were 
found to be amebe and ciliates, for they were killed by 
partial sterilization. 1 

527. Destruction of soil protozoa may explain benefit 
from soil " firing '" and deep plowing. — The preceding 
observations afford a probable explanation of a part of the 
beneficial results following the old practice of " firing '-'■ 
or burning soils ; and also the practice of the Bombay 

1 Russell, E. J., Science, 36 (1913), 520. 



CHLOBIN AND OTHER SUBSTANCES 365 

tribes, who were accustomed to burn rubbish with as much 
of the surface soil as possible before sowing their seed ; for 
such treatment would be highly destructive to protozoan 
life. 

It has since been claimed by Loew that the protozoa 
can probably only exist on or near the surface layers of 
such soils as are very compact, for the reason that the 
bacteria would be likely to render the store of air at the 
lower levels unfit for the respiration of the many proto- 
zoa. Nevertheless, in the Rothamsted soil, amebe are 
found at considerable depths. It may nevertheless be 
true that they exist chiefly in the surface layers of other 
soils. If this be true, the suggestion of Loew's might ex- 
plain some part of the benefit sometimes resulting from 
deep plowing, as compared with a shallow working of 
the soil by harrowing, since the protozoa would be trans- 
ferred thereby to the lower levels and would possibly be 
largely destroyed, thus giving a better chance for the 
development of the beneficial bacteria and for the rapid 
accumulation of an abundance of quickly available nitro- 
gen. 

528. The general applicability of soil disinfection 
doubted by Loew. — Notwithstanding that Loew admits 
the possible correctness of the conclusion of the Rotham- 
sted investigators, and the possibility of the usefulness of 
such treatment in special cases, he does not think that it 
will admit of general application ; furthermore, he points 
out the chance for the increase of possibly harmful as well 
as of beneficial organisms, as a result of sterilization. It 
is asserted, however, by Russell 1 that, " The improvement 
in the soil is permanent ; the high bacterial numbers being 
kept up even for 200 days or more." 

1 Science, 37 (1913), 519. 



366 FERTILIZERS 

529. The chlorid of lime treatment of soil tried by Loew. 

— In connection with the study of a soil which had become 
sick for lilies, Loew made a trial of carbon disulfid, tri- 
cresol, potassium permanganate, and chlorid of lime. It 
was found that beneficial results followed the use of all of 
these substances, but that chlorid of lime was the most 
effective and the least costly of them all. Since this is 
perhaps the first time that chlorid of lime (bleaching 
powder) has ever been used for this particular purpose, it 
may be stated that to an area 1.5 meters long and 1 meter 
wide, 100 grams of chlorid of lime were applied, dissolved 
in 5 liters of water. A part of the solution was spread 
over the surface, and the remainder was poured into holes 
made in the soil. 



INDEX 



A. B. C. method of conserving hu- 
man excrement, 17. 

Abraumsalz, 7. 

Acid phosphate, definition of, 201 ; 
sometimes dyed black, 208. 

Acid soils yield dark extracts with 
ammonium hydroxid, 268. 

Acids, fatty, in guano, 76. 

Actinomycetes as decomposers of 
humus, 39. 

Aerobacter, 42. 

Aerobic organisms active in dung, 
42. 

Ahlendorff & Co., 82. 

Ahnfeldtia plicata, 66, 231. 

Aikman, 344. 

Albinus, 165. 

Algae, marine, see sea-weeds. 

Algerian phosphates, 181, 182 ; 
composition of, 182 ; contain 
little iron and alumina, 182 ; 
good effect of, on "Hochmoor" 
soils, 182. 

Alkali, black, 334 ; is sodium car- 
bonate colored with vegetable 
matter, 334. 

Alsa menhaden, 88. 

Aluminum and iron silicates in 
phosphates sometimes objection- 
able, 221. 

Aluminum phosphate, 185 ; action 
of water on, 186, 188 ; artificial, 
solubility of, 186 ; efficiency of, 
increased by roasting, 185, 186 ; 
solubility of, affected by acid and 
alkaline solutions, 188 ; solubility 
in citric acid, 186 ; solubility in- 
creased by ammonium salts, 186 ; 
solubility in oxalic acid, 186. 



Alunite of little value as a fer- 
tilizer, 243. 

Amebe, destroyed by disinfectants, 
destroy microbes, 363. 

Amidase, use in treating distillery- 
waste, 112. 

Amids in manure, 29. 

Ammonia, absorbed by soil, 30 ; 
absorbed by various substances, 
31 ; fermentation in soils pro- 
moted by destroying protozoa, 
363 ; how held in soils, 30, 31 ; in 
manure, 29 ; preserved by gyp- 
sum, 32 ; said to be expelled from 
soils by lime, 283, 284 ; synthetic, 
production of, 146 ; volatiliza- 
tion of, 20. 

Ammonification, method of Lipman 
for determining nitrogen avail- 
ability by, 124. 

Ammonite, 94. 

Ammonium chlorid, early use of, at 
Rothamsted, 7 ; see chlorids. 

Ammonium nitrate costs little for 
transportation per unit of nitro- 
gen, 146 ; rarely used for manu- 
rial purposes, 146. 

Ammonium salts, first employed as 
manures, 7 ; synthetic production 
of, 146. 

Ammonium sulfate, absorption of, 
by soils, 148, 149 ; aids in ren- 
dering certain grasses dominant, 
155, 156 ; availability of, deter- 
mined by Wheeler and Hartwell, 
119; appearance of, 147; com- 
position of, 147, 148 ; conditions 
produced by, in acid soils not 
equally toxic to all plants, 153, 



367 



368 



INDEX 



154, 155 ; develops acidic condi- 
tions, 149 ; early use of, at Roth- 
amsted, 7 ; effects double decom- 
positions in the soil, 151 ; effect 
of, on maturity of plants, 157 ; 
efficiency of, as a fertilizer, 150 ; 
exhausts soils of lime, 149, 158 ; 
fleeting in effect, 158, 159 ; gives 
better results than nitrates in 
later stages of growth of some 

_ plants, 160 ; importance of the 
effect of, on the soil reaction, 151 ; 
impurities in, 147, 148 ; influence 
of soda in comparisons of, with 
nitrate of soda, 151 ; leaches less 
readily than nitrates, 159 ; liber- 
ates plant food, 158 ; manufac- 
ture of, 147 ; may cause injury 
on light calcareous soils, 159, 160 ; 
may cause partial sterility on ex- 
ceedingly acid soils, 152 ; may 
cause the suspension of certain 
bacterial activity, 157, 158 ; 
must not be mixed with certain 
alkaline substances, 148 ; nitro- 
gen of, fixed by microorganisms, 
149, 150 ; on acid soils drives out 
clover and certain grasses, 156 ; 
reaction of, with calcium carbo- 
nate, 149 ; reacts with zeolites, 
149 ; results with, in Rhode 
Island, 152 ; results with, in Wo- 
burn, England, 152. 

Amylobacter, 42. 

Anaerobic bacteria in manure, 39. 

Anaerobic organisms active in 
dung, 42. 

Anderson, 231. 

Anduard, A., and Anduard, P., 
355 

Anhydrit, 236. 

Antiseptics, as preservatives of 
manure, 34 ; in manure disad- 
vantageous, 37. 

Apatite, action of carbonic acid on, 
178 ; action of water on, 178 ; 
another name for phosphorite, 
175 ; composition of, 177, 178 ; 
distribution of, in soils, 175 ; oc- 



currence of, 177 ; utilization of, 
by process of Palmaer, 178. 

Aristotle, 250. 

Artificial basic slag meal, 198. 

Ascophyllum nodosum, 66, 69. 

Ashes, see wood, lime-kiln, cotton 
seed. 

Aso, 331, 353, 355. 

Aspergillus amidase, 47. 

Atterberg, 140, 318, 345, 346. 

Atwater, 5. 

Aubury, 297. 

Available phosphoric acid, see phos- 
phoric acid. 

Azotin, 94. 

Azotobacter chroococcum, 134, 135. 

Bacillus amylobacter, 43 ; arce, 47 ; 
boocopricus, 44 ; erythrogenes, 45 ; 
fermentationis cellulosm, 43 ; fluo- 
rescens, 42 ; fluorescens liquefa- 
ciens, 47 ; mesentericus ruber, 38, 
42, 43 ; methanigenes, 43 ; pas- 
teuri freudenreichii, 45 ; puncta- 
tum, 42 ; suaveolens, 42 ; subtilis, 
38 ; thermophilus grignoni, 38. 

Backhaus and Cronheim, 36, 38. 

Bacteria, aerobic, 38 ; aid ammoni- 
acal fermentation, 38 ; anaerobic 
in manure, 39 ; denitrifying, 
action of, on cellulose, 43 ; de- 
stroyed by protozoa, 40 ; increase 
of, accompanies increased am- 
monification after soil disinfec- 
tion and heating, 364 ; in manure 
decrease gradually, 37. 

Bacterial activity, effect of sulfate 
of ammonia on, 156, 157. 

Baker Island guano, 77. 

Barilla, 232. 

Barley, best lime-magnesia ratio 
for, 331 ; effect of manganese on, 
354 ; manganese salts in moder- 
ate amounts toxic to, 354. 

Barn-yard manure, see manure. 

Basic cinder, see basic slag meal. 

Basic slag meal, artificial, 198 ; 
care in mixing with ammonium 
salts and with organic nitrog- 



INDEX 



369 



enous substances, 196, 198 ; con- 
stitution of, 194, 195 ; contains 
less free lime than earlier, 194 ; 
discovery of process for making, 
8 ; effect of fineness of, 193 ; im- 
proves the physical condition of 
certain soils, 195 ; on clayey 
soils, 195 ; influence of silica on 
availability of, 192 ; ingredients 
of, 193 ; methods of determining 
the availability of, 192, 193; 
methods of determining free lime 
in, 194 ; not to be confused with 
blast furnace slag, 191 ; on acid 
pasture lands brings in clover, 
196 ; on acid uplands action ideal, 
196 ; on peat and muck soils, 
195 ; other names for, 191 ; over- 
production of, in Europe, 8 ; prac- 
tical use of, 195 ; probably not a 
tetracalcium phosphate, as at 
first supposed, 195 ; process of 
manufacture of, 191 ; range in 
composition of, 192 ; varies in 
availability, 192. 

Beans, best lime-magnesia ratio for, 
332 ; kidney, effect of manganese 
on, 355 ; unlike as to effect of lime 
on, 308. 

Beatson, 75. 

Belgian phosphate, 180. 

Bell, see Cameron. 

Benecke, 342. 

Bergen, 231. 

Bergstrand, 231. 

Berkeland and Eyde, 8, 126. 

Bernadini and Corso, 331. 

Bertrandj 354. 

Beseler, 143. 

Bessemer process for the manufac- 
ture of steel, basic slag a by- 
product of, 8. 

Bird manure, see Mago and Cato. 

Birner and Lucanus, 336. 

Black alkali, see alkali. 

Blood, crystallized, 97 ; dried, 
process for preparing, 97, 98 ; 
dried, availability of, 98, 99 ; 
dried, hygroscopic, 98 ; dried, 

2 B 



nitrogen availability of, 122 ; 
dried, red, chemical composition 
of, 97 ; dried, red, nitrogen con- 
tent of, 96 ; dried, red, sometimes 
adulterated, 96, 97. 

Bogdanov, 359. 

Bolley, 297. 

Bone, a favorite, with American 
farmers, 169 ; ash of, 167 ; black, 
dissolved or vitriolated, 169 ; 
chemical composition of, 166, 167, 
206 ; disintegration of, by fermen- 
tation, 169 ; dissolved, 206 ; 
early use of, as a manure, 165 ; 
effect of steaming on nitrogen 
content of, 168 ; effect of steam- 
ing on, 206 ; effect of steaming on 
phosphoric acid content of, 168 ; 
gathered from battlefields, 166 ; 
organic framework of, 167 ; other 
elements in, 166,167; raw, 168; 
raw more available than steamed 
on some soils, 169 ; removal of 
fat from, 167 ; replaced largely 
at present by acid phosphate, 
170 ; steamed, 168 ; treatment 
of, with sulfuric acid, 202 ; waste 
from industries, 168, 169 ; 
weathered, composition of, 167. 

Bone-black, dissolved, largely re- 
placed by acid phosphate, 206; 
treatment of with sulfuric acid, 
206. 

Bone meal, gradually improves 
acid soils, 170 ; the reverted 
phosphoric acid of, 170, 171 ; the 
soluble phosphoric acid of, 170 ; 
too slow to replace lime for the 
correction of soil acidity, 170. 

Bone tankage, see tankage. 

Bonnet, 2. 

Boussingault, 3, 6, 103, 282, 311. 

Bradley, see Lovejoy. 

Braezeale, 349. 

Brandt, 165. 

Bretfield, 317. 

Brewer's grains, the composition 
of, 111. 

Bristles, the composition of, 103. 



370 



INDEX 



Brooks, 174, 241, 242. 

Brown, 276. 

Buch, 212. 

Buckland, 178. 

Buckwheat, the best lime-magnesia 

ratio for, 331. 
Bunge, 335. 
Burchard, 46. 

Cabbage, best lime-magnesia ratio 
for, 331. 

Calcium acetate, effect of, on potato 
scab, 301. 

Calcium carbide, 161 ; use in com- 
bining nitrogen, 8. 

Calcium carbonate, compared with 
burned lime, 275, 276 ; compared 
with burned lime in Pennsylvania, 
275 ; depresses ammonification 
of cotton-seed meal, 285 ; effect 
of, on potato scab, 301 ; effect of, 
on the solubility of iron phosphate 
in soils, 190 ; prevents the red- 
dening of blue litmus paper by 
fine soil particles, 270 ; stimu- 
lates the ammonification of dried 
blood, 285 ; see also limestone, 
ground. 

Calcium chlorid, effect of, on potato 
scab, 301 ; see chlorids. 

Calcium cyanamid, a new product, 
161 ; changes in, taking place in 
the soil, 162 ; compares favorably 
with ammonium sulfate as a fer- 
tilizer, 163 ; decomposed by high 
steam pressure, 161 ; dicyanamid 
formed from, 163 ; first works for 
the manufacture of, 162 ; gradu- 
ally decomposes, yielding am- 
monia, 162 ; has an ultimate 
basic effect on soils, 163 ; how 
produced, 8 ; may be used in the 
manufacture of creatin, 163 ; may 
be used in the manufacture of 
urea, 163 ; output of, 164 ; 
process for the manufacture of, 
161 ; sold mixed with peat, 163 ; 
toxic in its action, at the outset, 
163. 



Calcium-magnesium ratio, effect of, 
on higher plants, 286 ; possible 
effect of, on nitrification of organic 
substances, 285. 

Calcium nitrate, a new fertilizer, 
125 ; a result of cheap electricity, 
125 ; as a carrier of lime, 128 ; as 
a fertilizer, 128 ; at first too 
hygroscopic, 127 ; chemical com- 
position of, 127, 128 ; conserves 
* lime supply of soils, 128 ; injury 
to workmen and horses, in apply- 
ing earlier product, 128 ; price 
based on that of nitrate of soda, 
129 ; process for making less 
hygroscopic, 127 ; process of 
manufacture, 126, 127 ; tendency 
in soils the opposite of ammonium 
sulfate, 128. 

Calcium oxalate, effect of on potato 
scab, 301. 

Calcium salts, like sodium chlorid, 
liberate potash, 338. 

Calcium sulfate aids the nitrification 
of urine, 285. 

Cameron, 210, 211, 251, 268; and 
Bell, 190, 212, 314 ; and Hurst, 
186, 189, 214; and Seidell, 211, 
212. 

Carbohydrates, destruction of, in 
dung, 41. 

Carbon disulfid, as a preservative 
of manures, 34 ; believed to pre- 
vent denitrification, 362 ; cures 
soils which are vetch, clover, and 
alfalfa, "sick," 362, 363; idea of 
Whitney concerning, 362 ; not 
the only unusual compound to 
show benefit on soils, 363 ; often 
increases crops, 361 ; shown to 
check excessive nitrification, 362 ; 
many theories regarding action 
of, have been suggested, 361, 362 ; 
treatment of soils with, costly, 
362 ; view of Oberlin concerning, 
361. 

Carbonato of lime, see calcium 
carbonate ; also limestone, 
ground. 



INDEX 



371 



Carbonate of potash, 241, 242; on 
acid soils superior to muriate, 
242. 

Carbonate of soda, see sodium car- 
bonate. 

Carnallit, 236, 237 ; composition of, 
237. 

Caro, see Frank. 

Carrots, effect of manganese on, 355. 

Castor pomace, composition of, 
110; nitrogen^ availability of, 
122. 

Catalysis, as an aid in the synthetic 
production of ammonia, 146; re- 
lation between, and oxidation not 
yet clear, 355. 

Catalytic substances, 9. 

Cato, 1. 

Caustic magnesia, see magnesia, 
caustic. 

Cellulose, amount in manure, 41 ; 
destroyed by aerobic bacteria, 
43 ; destruction by anaerobic 
organisms in manure, 43. 

Cereal and other seed by-products, 
109, 110. 

Cereals, best lime-magnesia ratio 
for, 331. 

Chalk, early use of, 1. 

Chamber or wet acid process, 100. 

Chemicals and manures, factors 
governing the use of, 62. 

Chincha Island guano, 78, 83. 

Chinese, use of manures by, 1. 

Chittenden, 345. 

Chlor-apatite, 177. 

Chlorid of lime, 40 ; amounts of, to 
apply, 366; cured lily "sick" 
soils, 366 ; treatment of soils 
with, by Loew, 366 ; mode of 
applying, 366 ; more effective and 
cheaper than carbon disulfid, tri- 
cresol, or potassium permanga- 
nate, 366. 

Chlorids, claimed by Nobbe to help 
buckwheat, 247 ; claimed by 
Pfeiffer to help potatoes, 247 ; 
found by Pagnoul bad for pota- 
toes, 247 ; ill effects of, due to 



lack of carbonates, 248 ; ill 
effects of, in potassium salts, 246 ; 
Loew's explanation of ill effects 
of, 246 ; not good for certain 
crops, 246 ; opposing views con- 
cerning, 247 ; reasons for divers 
opinions concerning, 247, 248, 
249 ; use of, increases the need of 
lime, 248 ; views of Griffiths as 
to ill effects of, 247 ; views of 
Nobbe concerning, discredited by 
A. Mayer, 247. ' 

Chlorin, a, non-essential element, 
357 ; occasional slight benefit 
claimed for, 357. 

Chloroform, effect of, on soils, 363. 

Chrondrus crispus, 66, 73, 231. 

Cipley, phosphates from, 181. 

Cladostephus verticillatus, 66, 231. 

Cocoons, 108 ; composition of, 108. 

Cod waste, 88. 

Colombian guano, 80. 

Comey, 327. 

Common crab, composition of, 92. 

Common salt, see salt. 

Compounds, definite, definition of, 
250. 

Coniferous trees, absorbent power 
of needles of, 27. 

Cook, 242. 

Copeland, 255, 342. 

Coprolites, a term sometimes used 
improperly, 179 ; appearance of, 
179 ; composition of, 179 ; dis- 
covery of, in England, 7 ; distri- 
bution of, 179 ; origin of name of, 
178 ; sometimes of so-called con- 
cretionary origin, 179 ; where 
found, 178. 

Coquilles animalisees, 93 ; a mix- 
ture of mollusks and star-fish, 93. 

Corso, see Bernadini. 

Cotton, action of, on blue litmus 
paper, 268, 269. 

Cotton-seed hull ashes, composi- 
tion and use of, 229 ; once used 
largely for tobacco, 228. 

Cotton-seed meal, 110; composi- 
tion of, 110; nitrogen, avail- 



372 



INDEX 



ability of, 122 ; used for cotton, 
tobacco, and sugar cane, 110. 

Cotton-waste, absorbent power of, 
28. 

Coutejean and Guitteau, 336. 

Coville, 281. 

Cow manure, see manure. 

Crab, see common crab. 

Crangon vulgaris, 91. 

Cress, sulfur in, 357. 

Cronheim, see Backhaus. 

Crookes, 125. 

Curry, see Morse. 

Cushman, 243. 

Daikuhara, 332. 

Dassonville, 317. 

Davy, 3. 

Deherain, 40, 56, 58, 159, 216, 267, 
280, 335 ; and Dupont, 48. 

Denitrification, an anaerobic pro- 
cess, 265 ; greater if much ma- 
nure is used, 58, 59 ; various 
factors affecting, 59, 60. 

Den treatment of phosphates, 204. 

De Ruyter de Wild, see Sjollema. 

De Sassure, 3, 7. 

Deutsche Landwirthschafts Gesell- 
schaft, 57. 

Devil's apron, 66, 67. 

De Vries, 255. 

Diastatic action in manure, 42 ; 
caused by molds and actinomyce- 
tes, 42, 43. 

Dicalcium phosphate, made by 
partial acidulation of bone, 202 ; 
see also phosphate. 

Dietzell, 47. 

Dillisk, 66, 68. 

Diorite, amount of soda in, 334. 

Disinfectants, destroy soil amebe, 
363. 

Disinfection of soils not believed by 
Loew to have general applica- 
tion, 365 ; claimed by Russell to 
have lasting effects, 365. 

Dissolved bone, see bone. 

Distillery waste wash, a source of 
nitrogen, 111 ; Effront's process 



of treating, 112; industrial utili- 
zation of, 111 ; Vasseux's process 
of treating, 111. 

Dolomite, 263, 332 ; composition 
of, 263. 

Dorsch, see Wagner. 

Double carbonate of potash and 
magnesia, analysis of, 241 ; to be 
avoided on highly magnesian 
soils, 241; useful on acid soils, 
241. 

Double manure salt, see sulfate of 
potash, low grade. 

Double sulfate of potash and mag- 
nesia, 240, 241, 332; costs more 
than muriate, 240 ; has given 
good results with apple trees, 241 ; 
magnesia content of, 240, 241 ; 
to be avoided on highly mag- 
nesian soils, 240. 

Dried blood, availability of, deter- 
mined by Wheeler and Hartwell, 
119 ; see also blood. 

Dry spot, see oats. 

Duhring, 41. 

Dulse, 66, 68. 

Dung, changes in non-nitrogenous 
matter of, 41 ; collecting and car- 
ing for, 20 ; early Use of, 1 ; 
effect of feed and age of animal 
on, 19 ; terms used in discussing, 
48, 49, 50 ; see also manure. 

Dupe, 359. 

Dupont, 38 ; see also Deherain. 

Dusart and Pelouze, 212. 

Dyer, 222, 251, 337. 

Dymond, 359. 

Eber, W., 49. 

Eckenbrecher, 115. 

Eel-grass, 69, 231. 

Emmerling, 143. 

Enzymes, oxidizing, manganese in, 

354. 
Eremacausis, 49. 
Erlwein, 129. 
Excrement, Bible reference to, 11 ; 

solid, amount per day, 12, 13. 
Excrement, human, 10 ; A. B. C. 



INDEX 



373 



method of conservation of, 17 ; 
care in using, 18 ; conservation 
of by Orientals, 14 ; conservation 
of, in Paris, 14, 15 ; disposal of, in 
Europe, 13, 14, 15 ; number of 
microorganisms in, 35 ; Sinder- 
mann's method of disposal of, 17 ; 
treatment with burned lime, 16, 
17. 
Eyde, see Berkeland. 

Farm manures, see manures. 

Fats, decomposition of, in manure, 
44; destruction of, in dung, 41. 

Feathers, 103 ; composition of, 103. 

Feces, see excrement. 

Feldspar, of little value as a direct 
fertilizer, 243 ; shown by Hart- 
well and Pember to have no prac- 
tical value, 243, 245 ; value 
claimed for it by Cushman, 243. 

Felt refuse, 107 ; composition of, 
107 ; use as a manure, 107. 

Ferments, use of, in treating dis- 
tillery waste, 112. 

Ferric phosphate, 188 ; solubility of 
artificial, in various substances, 
188, 189. 

Feuille, 75. 

Finger-and-toe disease, 299. 

Fish, as a source of phosphoric acid, 
172; composition of, 172 ; needs 
supplementing, 91 ; nitrogen 
availability in, 122 ; scrap may 
be used without treatment, 91. 

Fish guano, see guano, fish. 

Fish scrap, acts quickly in warm, 
moist climates, 91 ; acts slowly 
in cold climates, 91 ; best on 
light soils, 91 ; value depends 
upon the climate and soil, 91. 

Fish waste, in Norway, 88 ; water 
in, 89. 

Flagellatse devour microbes, 363. 

Flax, best lime-magnesia ratio for, 
332. 

Floats, action of manure on, 173 ; 
effect of liming on availability of, 
174, 175; how to use, 174; 



nature of, 173 ; soils the most 
useful on, 173. 

Florida phosphates, 183. 

Fluor-apatite, 177. 

Fluorids as preservatives of ma- 
nures, 34. 

Forchhammer, 231. 

Fourcroy and Vauquelin, 45. 

Frank and Caro, 8, 161. 

Frankland, 131, 159. 

Fraps, 186. 

French phosphates, 180. 

Frezier, 75. 

Fucus, see Ascophyllum . 

Fukutome, 352. 

Furuta, 331. 

Galapagos guano, 80. 

Garbage tankage, see tankage, gar- 
bage. 

Garola, 353. 

Gas-house lime, see gas lime. 

Gas-lime, 314. 

Gasparin, 310, 311. 

Genter, see Jordan. 

Gerlach, 186, 189, 288. 

German potash salts, discovery of, 
in Germany, 7 ; impurities asso- 
ciated with, 7. 

Giglioli, 47, 352 ; and Rousset, 356. 

Gilbert, see Lawes. 

Gilchrist, see Thomas. 

Gile, 286, 302, 321, 332. 

Girard, 361 ; see Miintz. 

Glue, substances containing, some- 
times rendered less available by 
steaming, 106. 

Gluten feed, composition of, 111. 

Godechens, 230, 231. 

Goessmann, 85, 92, 100, 107, 109 

Gohn, 165. 

Goodale, 342. 

Goodwin, see Russell. 

Grandeau, 273, 311. 

Granite, amount of soda in, 334. 

Granitic soil, soon shows need of 
potash, 338. 

Greensand, 242 ; a sea-bottom de- 
posit, 242 ; composition of, 242 ; 



374 



INDEX 



decomposed by hydrochloric acid, 
242 ; has value as a manure, 242 ; 
may exchange one base for an- 
other, 243 ; of possible magmatic 
origin, 242 ; proposed fusion with 
calcium chlorid, 243 ; slow in its 
manurial action, 242. 

Griffiths, 247, 339. 

Guanin in guano, 76. 

Guano, a poorly balanced manure, 
83 ; adulteration of, 81 ; Baker 
Island, 77; Chincha Island, 78, 
81 ; chemical composition of, 76, 
77, 83 ; Colombian, 80 ; color of, 
78 ; composition of, affected by 
climate, 77 ; distribution and 
sources of, 79, 80, 81 ; early ex- 
periments with, 75 ; early use of, 
75 ; effect of, on physical char- 
acter of soil, 79 ; Galapagos, 80 ; 
introduction into England, 6 ; 
introduction into Europe, 75 ; 
Ichaboe, 81 ; Lobos, 81 ; manner 
of using, 82 ; Maracaibo, 80 ; 
Mejillones, 77 ; nature of, 76 ; 
origin of name of, 75 ; Peruvian, 
81 ; physical character of, 78 ; 
rectified or dissolved, 81. 

Guano, bat, appearance of, 83 ; 
chemical composition of, 84 ; 
distribution of, 84 ; needs sup- 
plementing, 85 ; precautions in 
purchasing, 84 ; unlike others, 
83 ; where found, 84. 

Guano, fish, long used as a manure, 
86 ; special processes for prepar- 
ing, 86, 87 ; use of, as fertilizer, 
86 ; wastes in Japan, 87 ; wastes 
in Newfoundland, 87. 

Guano, horse foot, see horse-foot 
guano. 

Guano, phosphatic, 179, 180. 

Guano, whale, 89, 90 ; fish avail- 
ability of, 90 ; how applied, 90. 

Guitteau, see Coutejean. 

Guper, 35. 

Gypsum, as a renovator of black- 
alkali soils, 314 ; aids nitrifica- 
tion in alkaline media, 313, 314; 



an indirect fertilizer, 311 ; as a 
preservative of ammonia, 32, 33 ; 
as an oxidizing agent, 313 ; beets 
helped by, in Rhode Island, 310; 
early use of, 309 ; effect of, on the 
solubility of lime, 314; factors 
determining choice of, 312, 313 ; 
Gasparin's experiments with, 310, 
311 ; good effect of, on clover and 
other plants, 309, 310; holds 
ammonia, 313 ; in gas-lime, 314 ; 
liberates potash, 311 ; may be 
changed to calcium carbonate in 
the soil, 312 ; may sometimes 
help by furnishing sulfur, 312 ; 
methods of applying, 312 ; poorer 
than lime for acid soils, 311, 312 ; 
should be used in excess, 32, 33 ; 
sources of, 309 ; sources of, in 
soils, 309. 

Hair, composition of, 103. 

Hair, tannery, composition of, 

103. 
Hall, 29, 60, 61, 134, 140, 154, 155, 

258, 259, 286, 363. 
Hardy, 84. 
Hares and rabbits, composition of 

waste of, 104 ; waste of, 104. 
Hart and Peterson, 287, 358, 359. 
Hartwell, 328; and Pember, 173, 

243, 347 ; also see Wheeler. 
Headden, 134, 135; and Sackett, 

134. 
Heiden, 11, 13, 79, 100, 166, 277, 

278. 
Heinrich, 122. 
Hellriegei; 105, 347 ; and Wilfarth, 

5, 254, 347. 
Hendrick, 194. 
Hen manure, see manure. 
Herapoth, 352. 
High-grade sulfate of potash, see 

sulfate of potash, 
Hilgard, 31, 135, 314, 316, 324, 328, 

336. 
Hiller, 49. 
Hippuric acid, 21 ; decomposition 

of, in manure, 46. 



INDEX 



375 



Hochmoor, see peat. 

Hog manure, see manure. 

Hoof meal, after steaming, 100 ; 
and horn meal, adulteration of, 
1.00 ; composition of, 99 ; effi- 
ciency of, 100 ; nitrogen content 
of, 100; preparation of, 99. 

Hoof meal and horn meal mixed, 
99, 100 ; nitrogen availability in, 
122. 

Hopkins, 173. 

Horn and hoof meal, adulteration 
of, 100. 

Horn meal, 99; and hoof meal 
mixed, 99, 100 ; composition of, 
99 ; keratin in, 99. 

Horse-foot guano, composition of, 
92 ; lacking in phosphoric acid, 
92 ; nitrogen of, highly available, 
92 ; poor in potash, 92. 

Horse manure, see manure. 

Horseradish, sulfur in, 357. 

Hosaus, 160. 

Hoyermann, 192. 

Hudig, 297, 353. 

Hughes, 359. 

Human excrement, 10. 

Humboldt, Alexander von, 75. 

Hurst, see Cameron. - 

Hutchinson, see Russell. 

Huttemann, W., 35. 

Hydrated lime, 263 ; becomes re- 
carbonated, 264 ; nature of, 263 ; 
production of, 263. 

Hydrogen, fermentation in manure, 
43. 

Ichaboe guano, 81 ; composition of, 
81. 

Ichthyosaurus, 179. 

Idaho phosphates, 184. 

Indol, 49. 

Infusoria, soil, destroy microbes, 
363. 

Ingenhaus, 2. 

Insects, 108 ; composition of, 108. 

Insoluble phosphoric acid, see phos- 
phoric acid. 

Irish moss, 66, 73, 231. 



Iron, carbonate, changes color on 
oxidizing, 352 ; generally present 
in soils in sufficient quantities, 
351 ; higher salts of, reduced 
under anaerobic conditions, 351 ; 
lack of, in plants, causes chlorosis, 
351 ; lower salts of, oxidized on 
draining, 352 ; need of, by plants 
easily demonstrated, 351 ; salts, 
toxic, broken up by liming, 352 ; 
sulfids bad in gravels or sands 
used as coverings for bogs, 352 ; 
vital to the higher plants, 351. 

Iron and aluminium silicates some- 
times objectionable in phos- 
phates, 221. 

Iron phosphate, 185, 189, 190; 
formed in soils, 188. 

James, 231. 

Jamieson, 247. 

Jenkins, 231. 

Jentys, 47. 

Jodin, 360. 

Johnson, S. W., 102, 105, 122, 344. 

Joly, 210. 

Jordan and Genter, 344. 

Julie, 33. 

Kainit, as a preservative of manure, 
34 ; composition of, 237. 

Karmrodt, 77. 

Karsten, 234. 

Katayama, 331. 

Kellerman and Robinson, 285. 

Kelley, 353, 355. 

Kellner, 91, 115, 120, 169. 

Kelp, 65, 66, 67, 231. 

Kette, 40. 

Kieserit, 332 ; as a preservative of 
manure, 34 ; composition of, 237. 

King, 257, 341. 

King-crab, 92. 

Klaproth, see Vaquelin. 

Knop, 6, 319, 323. 

Koch and Pettit, 265. 

Konowalo, 331. 

Kunkle, 165. 

Kuntze, 135. 



374 



INDEX 



decomposed by hydrochloric acid, 
242 ; has value as a manure, 242 ; 
may exchange one base for an- 
other, 243 ; of possible magmatic 
origin, 242 ; proposed fusion with 
calcium chlorid, 243 ; slow in its 
manurial action, 242. 

Griffiths, 247, 339. 

Guanin in guano, 76. 

Guano, a poorly balanced manure, 
83 ; adulteration of, 81 ; Baker 
Island, 77; Chincha Island, 78, 
81 ; chemical composition of, 76, 
77, 83 ; Colombian, 80 ; color of, 
78 ; composition of, affected by 
climate, 77 ; distribution and 
sources of, 79, 80, 81 ; early ex- 
periments with, 75 ; early use of, 
75 ; effect of, on physical char- 
acter of soil, 79 ; Galapagos, 80 ; 
introduction into England, 6 ; 
introduction into Europe, 75 ; 
Ichaboe, 81 ; Lobos, 81 ; manner 
of using, 82; Maracaibo, 80; 
Mejillones, 77 ; nature of, 76 ; 
origin of name of, 75 ; Peruvian, 
81 ; physical character of, 78 ; 
rectified or dissolved, 81. 

Guano, bat, appearance of, 83 ; 
chemical composition of, 84 ; 
distribution of, 84 ; needs sup- 
plementing, 85 ; precautions in 
purchasing, 84 ; unlike others, 
83 ; where found, 84. 

Guano, fish, long used as a manure, 
86 ; special processes for prepar- 
ing, 86, 87 ; use of, as fertilizer, 
86 ; wastes in Japan, 87 ; wastes 
in Newfoundland, 87. 

Guano, horse foot, see horse-foot 
guano. 

Guano, phosphatic, 179, 180. 

Guano, whale, 89, 90 ; fish avail- 
ability of, 90 ; how applied, 90. 

Guitteau, see Coutejean. 

Guper, 35. 

Gypsum, as a renovator of black- 
alkali soils, 314 ; aids nitrifica- 
tion in alkaline media, 313, 314; 



an indirect fertilizer, 311 ; as a 
preservative of ammonia, 32, 33 ; 
as an oxidizing agent, 313 ; beets 
helped by, in Rhode Island, 310 ; 
early use of, 309 ; effect of, on the 
solubility of lime, 314; factors 
determining choice of, 312, 313 ; 
Gasparin's experiments with, 310, 
311 ; good effect of, on clover and 
other plants, 309, 310; holds 
ammonia, 313; in gas-lime, 314; 
liberates potash, 311 ; may be 
changed to calcium carbonate in 
the soil, 312 ; may sometimes 
help by furnishing sulfur, 312 ; 
methods of applying, 312 ; poorer 
than lime for acid soils, 311, 312 ; 
should be used in excess, 32, 33 ; 
sources of, 309 ; sources of, in 
soils, 309. 

Hair, composition of, 103. 

Hair, tannery, composition of, 

103. 
Hall, 29, 60, 61, 134, 140, 154, 155, 

258, 259, 286, 363. 
Hardy, 84. 
Hares and rabbits, composition of 

waste of, 104 ; waste of, 104. 
Hart and Peterson, 287, 358, 359. 
Hartwell, 328; and Pember, 173, 

243, 347 ; also see Wheeler. 
Headden, 134, 135; and Sackett, 

134. 
Heiden, 11, 13, 79, 100, 166, 277, 

278. 
Heinrich, 122. 
Hellriegei; 105, 347 ; and Wilfarth, 

5, 254, 347. 
Hendrick, 194. 
Hen manure, see manure. 
Herapoth, 352. 
High-grade sulfate of potash, see 

sulfate of potash, 
Hilgard, 31, 135, 314, 316, 324, 328, 

336. 
Hiller, 49. 
Hippuric acid, 21 ; decomposition 

of, in manure, 46. 



INDEX 



375 



Hochmcor, see peat. 

Hog manure, see manure. 

Hoof meal, after steaming, 100 ; 
and horn meal, adulteration of, 
100 ; composition of, 99 ; effi- 
ciency of, 100 ; nitrogen content 
of, 100; preparation of, 99. 

Hoof meal and horn meal mixed, 
99, 100 ; nitrogen availability in, 
122. 

Hopkins, 173. 

Horn and hoof meal, adulteration 
of, 100. 

Horn meal, 99 ; and hoof meal 
mixed, 99, 100 ; composition of, 
99 ; keratin in, 99. 

Horse-foot guano, composition of, 
92 ; lacking in phosphoric acid, 
92 ; nitrogen of, highly available, 
92 ; poor in potash, 92. 

Horse manure, see manure. 

Horseradish, sulfur in, 357. 

Hosaus, 160. 

Hoyermann, 192. 

Hudig, 297, 353. 

Hughes, 359. 

Human excrement, 10. 

Humboldt, Alexander von, 75. 

Hurst, see Cameron. • 

Hutchinson, see Russell. 

Hiittemann, W., 35. 

Hydrated lime, 263 ; becomes re- 
carbonated, 264 ; nature of, 263 ; 
production of, 263. 

Hydrogen, fermentation in manure, 
43. 

Ichaboe guano, 81 ; composition of, 
81. 

Ichthyosaurus, 179. 

Idaho phosphates, 184. 

Indol, 49. 

Infusoria, soil, destroy microbes, 
363. 

Ingenhaus, 2. 

Insects, 108; composition of, 108. 

Insoluble phosphoric acid, see phos- 
phoric acid. 

Irish moss, 66, 73, 231. 



Iron, carbonate, changes color on 
oxidizing, 352 ; generally present 
in soils in sufficient quantities, 
351 ; higher salts of, reduced 
under anaerobic conditions, 351 ; 
lack of, in plants, causes chlorosis, 
351 ; lower salts of, oxidized on 
draining, 352 ; need of, by plants 
easily demonstrated, 351 ; salts, 
toxic, broken up by liming, 352 ; 
sulfids bad in gravels or sands 
used as coverings for bogs, 352 ; 
vital to the higher plants, 351. 

Iron and aluminium silicates some- 
times objectionable in phos- 
phates, 221. 

Iron phosphate, 185, 189, 190; 
formed in soils, 188. 

James, 231. 

Jamieson, 247. 

Jenkins, 231. 

Jentys, 47. 

Jodin, 360. 

Johnson, S. W., 102, 105, 122, 344. 

Joly, 210. 

Jordan and Genter, 344. 

Julie, 33. 

Kainit, as a preservative of manure, 
34 ; composition of, 237. 

Karmrodt, 77. 

Karsten, 234. 

Katayama, 331. 

Kellerman and Robinson, 285. 

Kelley, 353, 355. 

Kellner, 91, 115, 120, 169. 

Kelp, 65, 66, 67, 231. 

Kette, 40. 

Kieserit, 332 ; as a preservative of 
manure, 34 ; composition of, 237. 

King, 257, 341. 

King-crab, 92. 

Klaproth, see Vaquelin. 

Knop, 6, 319, 323. 

Koch and Pettit, 265. 

Konowalo, 331. 

Kunkle, 165. 

Kuntze, 135. 



376 



INDEX 



Lachowiez, 188. 

Lahn phosphate, see Nassau. 

Laminaria digitata, 66, 67, 230. 

Laminaria saccharina, 65, 66, 230. 

Larbaletrier and Malpeaux, 318. 

Lawes, 75, 120 ; and Gilbert, 4, 5, 
6, 12, 158. 

Leather meal, nitrogen availability 
in, 120, 122. 

Leather waste, 100 ; availability 
of, 101 ; improved greatly by wet 
acid treatment, 100 ; less valu- 
able than it appears, 102 ; pre- 
pared, composition of, 101 ; 
roasted, 101 ; steamed, treat- 
ment of, 101 ; treatment of, with 
carbonates of the alkalies, 102. 

Lecanu, 11. 

Le Clerc, 352. 

Legumes, best lime-magnesia ratio 
for, 331 ; manurial value of, 
known to Varro and Columella, 1. 

Lehmann, 11, 160. 

Ley, H., 248, 328. 

Liebig, 3, 4, 6, 7, 79. 

Liernur process, for the preserva- 
tion of human excrement, 15. 

Lime, action of, on feldspar, how 
weakened, 288 ; action of, on 
worms and slugs, 267 ; aids hold- 
ing power of soil for bases, 289 ; 
amounts to apply, 292 ; analysis 
of burned, 262 ; application in 
Pennsylvania experiments, exces- 
sive, 276 ; as a liberator of potash, 
286 ; beneficial effects accounted 
for, 307 ; brings in nutritious 
grasses and clovers, 293 ; by 
addition to clay said to form 
zeolites, 289 ; carbonate less 
dangerous on sandy soils than 
magnesian carbonate, 285 ; caus- 
tic, attacks powdered quartz, 
289 ; cheapest basic treatment 
for soils, 270 ; chemical methods 
for determining need of, 270, 271 ; 
compounds transformed by 
plants, 295 ; corrects effect of 
excess of magnesia, 261 ; dolo- 



mitic, 263 ; effect of, on ammoni- 
fication, 262 ; effect of, on air cir- 
culation in soils, 265 ; effect of, 
on certain diseases, 262 ; effect 
of, on denitrification, 262; 265; 
effect of, on dry spot of oats, 297 ; 
effect of, on microscopic flora of 
soils, 262 ; effect of, on nitrifica- 
tion, 262 ; effect of, on nitrogen 
assimilation, 262 ; effect of, on 
nitrogen availability, 264, 265 ; 
effect of, on plants as compared 
with gypsum, 309, 310 ; effect of, 
on potato scab, 296, 299, 301, 
302 ; effect of, on size and yield 
of potatoes, 303 ; effect of, on 
soil texture, 265 ; effect of, on 
tobacco root rot, 297 ; effect of, 
on vegetable decay, 271, 272 ; 
effect of, on water, movement, 
266 ; essential to plant growth, 
261 ; excessive use of, to be 
avoided, 292 ; hastens crop ma- 
turity, 304, 305 ; hydrated, 263 ; 
indirect action of, illustrated, 286, 
287, 289 ; indirect manurial 
action of, 286 ; kinds of, used in 
agriculture, 262, 263 ; knowledge 
of, perpetuated in monasteries, 
2 ; lessens club-foot disease, 
297 ; liberates phosphoric acid, 
267 ; loses carbon dioxid in burn- 
ing, 262 ; losses, of, from soils, 
by leaching, 289, 290 ; magne- 
sian, 263 ; may cause injury to 
pineapples, 302 ; may improve 
light soils physically, 266 ; mis- 
cellaneous sources of, 264 ; 
needed for some plants, but bad 
for others, 306 ; not required to 
extent shown by some methods, 
271 ; occurrence of, 261 ; oxalate 
of, changed into carbonate in 
soils, 295 ; oxalate of, in plants, 
295 ; potash fixed after liberation 
by, 287, 288 ; practical applica- 
tion of, 292, 293 ; precipitated 
out in the plant as calcium oxa- 
late, 330 ; pure, compared with 



INDEX 



377 



magnesian, 293, 294 ; require- 
ments of different plants for, 307, 
308 ; should usually be intro- 
duced into the soil, 293 ; slaked, 
becomes quickly carbonated, 277, 
278 ; slaked, highly beneficial in 
Rhode Island, 276, 277; some- 
times excreted from plants as 
carbonate, 330 ; treatment of 
excrement with, 16 ; use of, in 
connection with phosphates, 266, 
267 ; use of, on mossy land, 293 ; 
use of, on pastures, 293 ; waste, 
from industries, 314, 315; where 
to spread, on the surface, 293. 

Lime, builders, see burned lime. 

Lime, burned, see burned lime. 

Lime-magnesia, ratios best for 
barley, 331 ; beans, 332 ; buck- 
wheat, 331 ; cabbages, 331 ; 
cereals, 331 ; flax, 332 ; legumes, 
331 ; maize, 331 ; mulberry 
leaves, 331 ; oats, 331 ; rice, 331 ; 
tobacco, 332; wheat, 331. 

Lime-nitrogen, 161. 

Lime, slaked, avoidance of use of, 
to conserve humus not always 
wise, 273, 274, 275; compared 
with calcium carbonate and marl, 
278, 289, 280; earlier believed 
not to carbonate quickly, 277, 
278 ; effect of, on potato scab, 
301 ; errors of Heiden concern- 
ing, 277, 278; if used properly, 
does not injure soils, 275 ; in- 
creases nitrogen content of humus, 
272, 273 ; good results from, 276, 
277 ; rotations of crops essential 
in connection with use of, 273. 

Lime, slaked and burned, concern- 
ing their expulsion of ammonia 
from soils, 282, 283 ; influence of, 
on nitrification, 283, 284, 285 ; in- 
troduction of, into acid peat sub- 
soils, 281 ; large amounts of 
slaked lime check nitrification, 
284; penetration of, into soils, 
280, 281, 282 ; views of European 
authorities concerning, 280. 



Lime and magnesia, percentage of, 
in crops and relation of, to yields, 
329, 330. 

Lime-kiln ashes, composition of, 
228. 

Lime-magnesia ratio found by Gile 
to vary widely without ill effects, 
332. 

Lime rock, see burned lime. 

Limestone, see burned lime. 

Limestone, burned, 263 ; changes 
produced in, by burning, 262 ; 
composition of, 263 ; distribu- 
tion of, 261 ; dolomitic, 263 ; 
effect of, on soils, 261. 

Limestone, coarse, compared with 
fine limestone, 290, 291 ; com- 
pared with marl, 290, 291. 

Limestone, magnesian, 332. 

Liming, need of, suggested by soil 
acidity, 268. 

Limulus Americanus, 92. 

Linseed meal, composition of, 110; 
nitrogen availability in, 122. 

Lipman, 124, 285, 286. 

Liquors, dark, in leachings of dung, 
52. 

List, 36. 

Litmus paper, action of cotton on, 
268 ; action of finely divided 
material on, 268, 269 ; reliability 
of, questioned, 268, 269. 

Litter, absorbent power of different 
kinds of, for water and ammonia, 
27, 31 ; ammonification of, 47; 
amounts of, to use, 26, 27 ; as an 
absorbent, 26 ; conserving power 
of, 28 ; cotton waste as, 28 ; in- 
fluence of, on manure, 19 ; leaves 
as, 27 ; microorganisms in, 36 
mosses as, 27 ; needles of conif- 
erous trees as, 27 ; oat straw as 
27 ; pea straw as, 27 ; peat as 
27, 31 ; sawdust as, 27, 31 ; soil 
as, 27, 31 ; spent tan as, 27 
wheat straw as, 27. 

Lobos guano, 83, 179 ; composition 
of, 179. 

Lobster refuse, 92; composition of, 92. 



378 



INDEX 



Loew, O., 246, 253, 285, 286, 294, 
316, 319, 321, 322, 323, 325, 330, 
363, 366 ; and Sawa, 354, 356. 

Loges, 143. 

Lovejoy and Bradley, 126. 

Lucanus, see Birner. 

Lupines, varying effect of lime on, 
308. 

Macrocystis purifera, 74. 

Maercker, 143, 157 ; and Schneide- 
wind, 30. 

Magnesia, a carrier of phosphorus 
in the plant, 316 ; aids in the 
translocation of starch, 316; and 
lime ratios in the soil, 321, 322, 
323 ; conflicting ideas concerning 
the action of, 317, 318, 319; 
essential to plant growth, 317; 
functions of, in the plant, 316, 
317 ; in Japanese soils, 321, 322 ; 
in Ohio soils, 322 ; lime ratio, 
method of determining, in soils, 
323 ; quantities in different parts 
of plants, 323 ; sources of, for 
fertilizer purposes, 332 ; theory 
of Loew concerning, 319, 320, 321. 

Magnesia, caustic, danger in using 
for a time, 324 ; gave good results 
the second year, 324 ; toxic at 
first, 326. 

Magnesia and lime in relation to 
yields, 329, 330. 

Magnesian lime, more dangerous 
on light than on heavy .soils, 327 ; 
possible danger in using, 326, 
327 ; precautions in use of, 
294. 

Magnesian limestone, 332. 

Magnesite, 332. 

Magnesium carbonate, aids am- 
monification of cotton-seed meal, 
285 ; artificial, more soluble in 
carbonated water than calcium 
carbonate, 327 ; depresses am- 
monification of dried blood, 285 ; 
may cause injury by its alkaline 
action, 327 ; natural, highly in- 
soluble, 328 ; newly >>rmed, a 



quicker corrective of acidity than 
dolomite or magnesite, 328, 329 ; 
solubility of artificial, 329 ; solu- 
bility of natural, 327, 328. 

Magnesium chlorid, concerning the 
alleged toxic action of, 323 ; ex- 
cessive amounts of, injurious, 
323 ; not always poisonous, 324, 
325 ; studies of, by Wheeler and 
Hartwell, 324, 325, 326. 

Magnesium fluor-apatite, 178; see 
Wagnerite. 

Mago, 1. 

Maize, best lime-magnesia ratio for, 
331 ; effect of manganese on, 
355. 

Malpeaux, see Larbaletrier. 

Malt sprouts, composition of, 110. 

Manganese, amounts of, safe to use 
per acre, 353 ; beneficial effects 
of, may be due to promoting 
oxidation, 355 ; cannot fully re- 
place iron in plant nutrition, 355, 
356 ; change in oxidation of, 
caused by roots, 355 ; dioxid 
found adhering to roots, 355 ; 
effect of, on carrots, 355 ; effect 
of, on kidney beans, 355 ; effect 
of, on potatoes, 355 ; effect of, on 
wheat, 355 ; exerts bleaching 
action on chlorophyl, 354 ; help- 
ful to maize, only in small 
amounts, 355 ; in Hawaiian soils, 
353 ; in plants studied by Le 
Clerc, 352 ; increases oxidase 
and peroxidase reactions, 354 ; in- 
creases yields of corn and wheat, 

352 ; may aid chlorophyl develop- 
ment, 355, 356 ; noted in plants 
by Herapoth, 352 ; plants unlike 
in endurance of, 353 ; presence 
of, in plants shown by Scheele, 
352 ; promotes development of 
plants grown in dilute solutions, 
354; restores "oat-sick" soils, 

353 ; review of experiments with, 
in plant nutrition, 356 ; salts of, 
increased growth of flax, 352, 
353 ; salts must be used cau- 



INDEX 



379 



tiously, 355 ; wide variations in 
amount of, in plants and soils, 
353, 354. 

Mangon, M. Herve, 72. 

Manure, amids in, 29 ; ammonia in, 
29 ; amount of cellulose in, 41 ; 
amount of pentosans in, 41 ; 
amount of starch in, 41 ; anti- 
septics disadvantageous as pre- 
servatives of, 37 ; barn-yard, 19 ; 
denitrification in, aided by certain 
substances, 57, 58 ; denitrifica- 
tion in, greater if used abun- 
dantly, 58, 59 ; effect of chloro- 
form on, 40 ; effect of heating on, 
40 ; effect of, on potato scab, 301 ; 
farm, 19 ; farm animals often 
kept on, 29 ; favors disintegra- 
tion of old sod, 63, 64 ; immediate 
incorporation of, with soil desir- 
able, 56 ; importance of strep- 
tococci in, 37 ; influence of litter 
on, 19 ; lacks effectiveness when 
fresh, 52 ; lasting qualities of, 60, 
61 ; liquid, preservation of, 53 ; 
losses of, in heaps and broad- 
casted, 56, 57 ; losses from, in- 
creased by bacteria from intes- 
tinal tract, 51 ; losses from, less 
in later stages of decomposition, 
51, 52 ; losses from, lessened, 
when moist and compact, 50, 51 ; 
losses from, lessened by packing 
and trampling, 28 ; losses of 
sugar in, 41 ; molds in, 39 ; 
nature and cause of losses occur- 
ring in, 50 ; necessity of moisture 
in, 53 ; practical utilization of, 
55 ; reason for even spreading of, 
63 ; stable, 19 ; storage of, versus 
direct application of, 55, 56 ; 
supplemented profitably by chem- 
ical fertilizers, 61, 62; time 
to spread, 57 ; treatment of, in 
Europe, 53 ; types of micro- 
organisms in, 37 : use of coarse, 
62, 63; waste of, by "fire- 
fanging " and otherwise, 20; 
yeasts in, 39. 



Manure, cow, adapted to certain 
greenhouse plants, 22 ; amount 
of, produced per cow, 23 ; chemi- 
cal composition of, 22 ; number 
of microorganisms in, 35 ; often 
improved by mixing with horse 
manure, 22. 

Manure, hen and pigeon, composi- 
tion of, 25 ; need supplementing, 
26 ; of superior value, 25 ; solid 
and liquid of, voided together, 
26 ; rich in nitrogen, 26. 

Manure, hog, amount of, produced 
per animal, 25 ; composition and 
value of, 24. 

Manure, horse, annual production 
of, per animal, 22 ; composition 
of, 21 ; ferments readily, 20, 21 ; 
litter used with, 21, 22 ; losses 
of, by "fire-fanging," 20, 28; 
methods of storage of, 22 ; num- 
ber of microorganisms in, 35. 

Manures and chemicals, factors 
governing use of, 62. 

Manure, solid, ammonification of, 
47. 

Manure salts, 237, 332. 

Manure, sheep, amount of, pro- 
duced per animal, 24 ; composi- 
tion of, 24 ; value of, 23. 

Maracaibo guano, 80. 

Marchand, 230, 231, 234. 

Margraff, 165. 

Marl, comparison of a low grade of, 
with slaked lime, magnesia, and 
oyster-shell lime, 279, 280 ; com- 
pared with coarse and fine lime- 
stone, 290, 291, 292; early use 
of, 1. 

Maturity of plants, effect of am- 
monium sulfate on, 157. 

Matzuschita, 36. 

Mayer, A., 139, 160, 246, 247, 340, 
343, 344, 345. 

McFarland, 74. 

Meat meal, Australian, 94; avail- 
ability of, 95; composition of, 
94, 95 ; little available for direct 
use, 95. 



382 



INDEX 



Pagnoul, 247, 335, 336. 

Palissy, 2. 

Palmaer, 178. 

Palmaer phosphate, 199 ; a dical- 
cium phosphate, 199 ; experi- 
ments with, in Sweden, 199 ; in- 
ferior to basic slag meal for peat 
soils, 200 ; on sandy and peat 
soils the immediate and residual 
effects of, equal those of super- 
phosphate, 199 ; process of manu- 
facture of, 199 ; solubility of, in 
ammonium citrate, 199. 

Passarini, 319, 337. 

Pasteur, 45, 49. 

Payen, 16; and Boussingault, 103. 

Pea straw, absorbent power of, 27. 

Pearl ash, see potassium carbonate. 

Peat, absorbent power of, 27, 31; 
see muck. 

Peat soils, failure of lime to pene- 
trate, 281. 

Pectin, decomposition of, in manure, 
43. 

Peligot, 335. 

Pelouze, see Dusart. 

Pember, see Hartwell, see Wheeler. 

Penicillium glaucum, 47. 

Pentosans, amounts of, in manure, 
41. 

Pepsin method for determining 
nitrogen availability, 123. 

Permanganate method for deter- 
mining nitrogen availability, 
123. 

Permanganate of potash, see potas- 
sium permanganate. 

Perraud, J., 362. 

Peruvian guano, 81. 

Petermann, 105, 115, 226. 

Peterson, C, 99 ; see Hart. 

Petlitt, 86. 

Pettit, see Koch. 

Pfeffer, 255, 342. 

Pfeiffer, Th., 247. 

Phonolite, of value as a fertilizer if 
finely ground, 243 ; less valuable 
than the German potash salts, 
243. 



Phosphates, artificial, from low- 
grade phosphates, 200 ; artificial, 
by bisulfate treatment, 201 ; 
artificial, from aluminum phos- 
phate, 201 ; choice of, affected 
by the soil and crop, 225, 226, 
227; den treatment of, 204; of 
Belgium, 180; of France, 180 
of Idaho, 184 ; of iron and alu- 
minum, 185, 186, 188, 189, 190 
of Montana, 184; of Northern 
Africa, 181; of Portugal, 181: 
of Russia, 181 ; of Tennessee 
184 ; of the islands of the Pacific 
180 ; of the Western States, 184 
of Western States favorably situ- 
ated, 185; of Wyoming, 184 
other artificial, 200 ; Palmaer 
199 ; relationship of the various 
203 ; Wiborgh, 198 ; Wolter's, 199 

Phosphate, acid, see acid phos- 
phate. 

Phosphate, dicalcium ; action of 
water on, 211, 212; action of, 
water on, increased by carbonic 
acid, 212. 

Phosphate, monocalcium ; action 
of water on, 208, 210, 211 ; help 
from liming after certain rever- 
sions of, 216; reversion of, 215; 
reversion of, with iron and alu- 
minum oxids often serious, 219, 
220 ; sometimes highly bene- 
ficial, 219. 

Phosphate, tricalcium; action of 
water on, 212, 213, 214; action 
of water on, increased by car- 
bonic acid, 213 ; oxids of alu- 
minum and iron in, are objec- 
tionable for superphosphate 
manufacture, 219 ; solubility and 
decomposibility of, increased by 
certain substances, 214. 

Phosphates of Florida, black river 
pebble, 183 ; bowlder, 183 ; com- 
position of, 183 ; land pebble, 
183 ; rock, 183. 

Phosphates of South Carolina, age 
of, 182 ; nodular, 182 ; of lime- 



INDEX 



383 



stone origin, 182; river, 182, 
183. 
Phosphatic guanos, 179, 180. 
Phosphoric acid, free; definition 
of term, 202 ; preparation of, 
from tricalcium phosphate, 202. 
Phosphoric acid, insoluble, 218. 
Phosphoric acid, reverted; avail- 
ability of, 217, 218 ; insoluble in 
water, 217; not all from dical- 
cium phosphate, 217. 
Phosphoric acid, soluble; advan- 
tages of, 215 ; after fixation may 
be highly available to plants, 
223 ; determination of, 214, 215 ; 
reversion of, 216. 
Phosphorite, see apatite. 
Phosphorus, discovery of, 165; 
found in bones, 165; found in 
pyromorphite, 165; from phos- 
phoric acid, 165; from seeds of 
mustard and cress, 165 ; in apa- 
tite, 165. 
Phyllophora membrani folia, 66, 231. 
Pigeon manure, see manure. • 
Pineapple, manganese in, 354. 
Pineapple chlorosis, caused by lime, 
303; cured by applying iron 
salts to the leaves, 302. 
Pine sawdust, power of, to absorb 

ammonia, 31. 
Plant nutrition, first experiments 

in, 2, 3. 
Plants, miscellaneous, effect of 

lime on, 307, 308. 
Pogys, see Menhaden. 
Polyhalit, 236. 
Polyides rotundus, 66, 231. 
Pomace, castor, composition of, 

110. 
Pond-weed family, 65. 
Popp, 243. 

Portuguese phosphates, 180. 
Potash, absorption of, in soils, may 
have several causes, 250, 251 ; 
contracts with American fertilizer 
manufactures, 235 ; deposits, oc- 
currence, and distribution of salts 
of, 235; deposits of salts of, in 



Germany, 234, 235, 236, 237; 
factors affecting absorption of, 
251, 252, 253; fixed in soil after 
liberation by lime, 287, 288 ; geo- 
logical age of deposits of salts of, 
236 ; history of the German salts 
of, 234, 235; in ash of, Indian 
corn cobs, 233 ; in potassium car- 
bonate, 233 ; in potassium nitrate, 
233 ; in sea-weeds, 66, 230, 231 ; 
in soils, replaces other bases, 
250 ; in tobacco stems, 232 ; 
little loss of, by leaching, 251 ; 
mines bought by Americans, 
235 ; retention of, by soils, 250 ; 
see potassium and potassium 
salts. 
Potassium, aids carbohydrate for- 
mation, 253; as a neutralizer 
and carrier in the plant, 255 ; 
cannot be fully replaced by 
sodium, 253 ; conserved in the 
soil by sodium salts, 260; defi- 
ciency of, more serious for some 
crops than for others, 259, 260; 
degree of replacement of, by 
sodium depends upon the kind 
of plant, 253 ; effect of a lack of, 
on plants, 258 ; effect of an' 
absence of, on Oxalis and Rumex, 
344; effect of, on photosyn- 
thesis, 254 ; effect of, on turgor, 
255 ; essential to plant growth, 
253 ; in alunite, 243 ; in feldspar, 
243 ; in greensand, 242, 243 ; in 
leucite, 243 ; in nepheline, 243 ; 
in phonolite, 243 ; increases the 
size of grain and amount of crop 
of cereals, 254 ; increases the leg- 
umes in mixed herbage, 258; 
good effect of, on legumes, 257, 
258; lessens vapor pressure in 
soils with beneficial effect, 254 ; 
may contribute a part to the 
"luxury consumption" of the 
plant, 256 ; may improve or in- 
jure the physical condition of the 
soil, 257 ; may increase surface 
tension, 256, 257 ; may lessen 



384 



INDEX 



evaporation, 257 ; may stimulate 
nitrogen assimilation by increas- 
ing carbohydrates within the 
plant, 258 ; necessary to combine 
with organic acids, 344 ; not the 
sole cure for clover sickness, 258 ; 
permanganate, effect of, on soils, 
363 ; salts act best in wet 
seasons, 259 ; silicate, 241 ; vari- 
ous functions of, 253. 

Potassium carbonate, 241, 242 ; 
sources of, 233 ; the chief im- 
purities of, 233 ; valuable for 
certain soils, 234. 

Potassium chlorid, see muriate of 
potash. 

Potassium magnesium carbonate, 
241 ; good for acid soils, 241. 

Potassium nitrate, as an incrusta- 
tion on some soils, 129 ; composi- 
tion of, 130 ; impurities of, 131 ; 
made artificially from nitrate of 
soda, 131 ; made in artificial 
niter beds, 130 ; manurial value 
known by the year 1669, 6 ; 
often economical as a fertilizer, 
131, 233; sources of, 129, 130; 
special uses of, 233 ; use of, per- 
mits the avoidance of chlorin, 
131. 

Potassium salts, alleged ill effects 
of chlorin of, 246, 247 ; German, 
duration of deposition of, 238 ; 
natural deposits of, elsewhere 
than in Germany, 238 ; removed 
from soil less readily than salts 
of sodium, 246 ; tabulated analy- 
ses of, 237. 

Potassium sulfate, composition of, 
237; fate of, in soil, 249; high 
grade, 240 ; low grade, 240, 241 ; 
reduced under anaerobic condi- 
tions, 249. 

Potatoes, effect of manganese on, 
355 ; size and yields of, increased 
by liming, 303, 304. 

Potato scab, cause of, 299 ; effect 
of barn-yard manure on, 301 ; 
effect of calcium oxalate on, 301 ; 



effect of calcium chlorid on, 301 ; 
effect of calcium sulfate on, 
301 ; effect of oxalic acid on, 
301 ; effect of slaked lime on, 
301 ; effect of sodium carbonate 
on, 301 ; effect of wood ashes on, 
301 ; fungus lives saprophytically 
in the soil, 301. 

Prianischnikov, 340. 

Priestley, 2. 

Proteins, sulfur in, 357. 

Protozoa, according to Loew can- 
not exist at the lower soil levels, 
365 ; destroy bacteria, 40 ; de- 
stroyed by certain substances, 
40 ; destruction of, may explain 
the benefit observed from firing 
soils, 364 ; found at considerable 
depths at Rothamsted, 365 ; 
may destroy bacteria, 39 ; may 
explain part of the gain from 
deep plowing, 364, 365. 

Pugh, 4. 

Putrefaction, 49. 

Pyridin or other similar compounds 
have been found in soot, 108. 

Pyrite in phosphates for superphos- 
phate manufacture objectionable, 
221. 

Quiros, Allier & Co., 75. 

Rabbits, see hares. 

Raleigh, Lord, 125. 

Redonda phosphate, 185. 

Reed, 282, 316. 

Reese, Jacob, 8. 

Remy, 173. 

Reuter, see Treadwell. 

Reversion of phosphates, reactions 
in course of, described, 218, 219, 
220, 221. 

Reverted phosphoric acid, see phos- 
phoric acid, reverted. 

Rhodymenia palmata, 66, 68, 230. 

Rice, best lime-magnesia ratio for, 
331. 

Ricome, 340. 

Ritthausen, 360. 



INDEX 



385 



Robinson, see Kellerman. 

Rossi, 129. 

Rousset, see Giglioli. 

Russell, and Goodwin, 29 ; and 

Hutchison, 40, 363. 
Rye, best lime-magnesia ratio for, 

331. 

Sachs, 356. 

Sackett, see Headden. 

Salamone, 355. 

Salfeld, 70. 

Salm-Horstmar, 344. 

Salt, common, 236 ; amount of, in- 
jurious to crops, 334 ; large 
amounts of, used in Great Britain, 
339 ; may indirectly cause solu- 
tion of vegetable matter, 340 ; 
reacting with calcium carbonate 
may produce sodium carbonates, 
340. 

Saltpeter, see potassium nitrate. 

Saltpeter waste, composition of, 
229 ; should be bought on analy- 
sis, 229. 

Salts, neutral, check dissociation, 
328. 

Salzthon, 236. 

Sawa, see Loew. 

Sawdust, absorbent power of, 27, 
31. 

Schacke, 243. 

Scheele, 165, 352. 

Schellmann, 47. 

Schenck, see Strasburger. 

Schneider, 186. 

Schneidewind, 347 ; see Maercker. 

Schreiber, see Smets. 

Schreiner and Sullivan, 355, 356. 

Schroeder, 354. 

Schucht, 220. 

Schultz, of Lupitz, 70, 248. 

Sea weeds, analyses of, 66, 230, 231 ; 
as affecting the need of lime, 72 ; 
barilla from, 232 ; chemical com- 
position of, 66, 230, 231 ; com- 
pared with farm-yard manure, 
72 ; composition of, at different 
seasons, 67, 68 ; composting of, 



73 ; effect of, on quality of crops, 
70', 71 ; especial attention called 
to, as a source of potash by the 
famous German-American potash 
contracts, 229 ; free from weed 
seeds, 72 ; may injure hops, to- 
bacco, and beets for sugar, 71 ; 
not well balanced as a manure, 
72 ; of chief importance in New 
England, 68 ; often improved by 
leaching, 71 ; often preferable to 
stable manure, 70 : of the Atlan- 
tic coast, 66, 230, 231; of the 
Pacific coast, 74, 232 ; potash in, 
66, 229, 230, 231; practical 
utilization of, 70 ; produce 
smooth potatoes, 70 ; quick in 
their action, 71 ; rapidity of 
growth of, 74 ; size of, 74 ; use 
in Europe, 66 ; value of, known 
to the ancients, 65 ; value of, 
limited by cost of handling, 69, 
70. 

Sennebier, 2. 

Severin, 33, 38, 40. 

Seyffert, 122. . 

Sheep manure, see manure. 

Shimper, 255, 317. 

Shoddy, composition of, 107 ; im- 
proves the physical condition of 
some soils, 107 ; use of, as a 
manure, 107. 

Shrimps, as a fertilizer, 91 ; lack- 
ing in phosphoric acid, 91. 

Siemens and Halske, 129. 

Silene orientalis, 307. 

Silica, an important constituent of 
plants, 359 ; content of, in the 
ash of plants sometimes 40 to 70 
per cent, 359 ; deposition of, 
checks sap diffusion, 360 ; may 
favor migration of phosphoric 
acid to the seed, 360 ; may have 
special value for plants, 359 ; may 
help form zeolites in soils, 359 ; 
may help some plants but not 
others, 360 ; may replace other 
ingredients of plants in their 
"luxury consumption," 360 ; may 



386 



INDEX 



support and protect the cell 
wall, 359 ; not found by Jodin 
to be essential to plants, 360. 

Silicate of potash, a valuable fer- 
tilizer, 241 ; analysis of, 241 ; 
manufacture of, discontinued, 
241 ; results with, in Massachu- 
setts, 241. 

Silk waste, nitrogen in, 104. 

Sindermann, 17. 

Sjollema, 335, 353 ; and De Ruyter 
de Wild, 41. 

Skatol, 49. 

Skinner, 75. 

Slugs, see worms. 

Smets and Schreiber, 339. 

Societa Generale per la Cianamide, 
162. 

Soda, absorbed by oats if potash is 
deficient, 336 ; as an indirect 
manure, 336 ; claimed to be 
sometimes absent in plants, 335 ; 
content of, in plants widely vari- 
able, 336 ; favors passage of phos- 
phoric acid into plants, 336 ; in 
feldspar, 333 ; liberates magnesia, 
337 ; presence of, in higher plants 
practically universal, 334, 335 ; 
said to be absent from potato 
tubers, 335 ; universally distrib- 
uted in nature, 334 ; used in the 
fertilizers may increase the 
amount in the plant, 336 ; see 
sodium, and sodium salts. 

Sodium, claimed by some to have 
acted only indirectly, 346 ; 
claimed to help by being a highly 
soluble carrier of nitrogen and 
phosphorus to the plant, 347 ; 
concluded by Stohmann to be 
essential to perfect plant develop- 
ment, 344 ; conclusions of Jor- 
dan and Genter concerning, 344, 
345 ; if essential to plants, minute 
quantities of, suffice, 344 ; in- 
creased crops one half when po- 
tassium was lacking, 346 ; may 
partly replace potassium as a 
combining and carrying agent in 



the plant, 344 ; potassium re- 
placed better by, than by cal- 
cium, 345 ; see soda, and sodium 
salts. 

Sodium carbonate, a residual prod- 
uct from the application of nitrate 
of soda to soils, 340 ; effect of, 
on potato scab, 301. 

Sodium chlorid, amounts of, in- 
jurious to crops, 334 ; an indirect 
manure, 337 ; effect of, on potato 
scab, 301 ; if it causes the for- 
mation of carbonates, it may de- 
flocculate soils, 341 ; in the air, 
333 ; liberates potash, 337, 338 ; 
seems to bring out the action of 
phosphates and nitrates, 337 ; 
sometimes aids by flocculating 
soils, 341 ; sources of, in the air, 
333. 

Sodium nitrate, see nitrate of soda. 

Sodium perchlorate, as an impurity 
in nitrate of soda, 136, 137. 

Sodium salts, benefit from, not 
always explained by liberation 
of potash, 349 ; benefit to crops 
from applying, 338, 339, 340; 
certain plants apparently not 
benefited by, 347 ; doubled the 
yield of mangel wurzels, 348 ; 
effect of, dependent on various 
conditions, 340, 341 ; effect of, 
on osmotic pressure, 342 ; experi- 
ments of Atterberg with, 345 ; 
experiments with, in Rhode 
Island, 348, 349, 350 ; facilitates 
movement of water toward the 
surface of the soil, 341 ; favor 
diastatic action, 345 ; frequently 
injurious, 339 ; increase phos- 
phorus percentages in the plant, 
338 ; increase surface tension, 
341 ; indirect manurial action of, 
impossible in water culture, 349 ; 
in the experiments of Hellriegel 
and Wilfarth, liberated potash, 
348 ; in the plant, protect from 
too rapid transpiration, 341 ; in 
water culture helpful, 349 ; may 



INDEX 



387 



lessen evaporation, 341 ; mineral 
sources of, 333, 334; more bene- 
ficial to some plants than to 
others, 339 ; of benefit to plants 
in the field, 348 ; outside the 
plant may lessen the water ab- 
sorbed, 341 ; possible manurial 
function of, 342 ; possible physio- 
logical functions of, 342 ; prac- 
tical significance of, in agriculture, 
350 ; precautions in connection 
with use of, in water culture, 349, 
350 ; substitution of, for a part 
of the potash in certain functions 
of plants, 342, 343 ; see soda, and 
sodium. 

Soft phosphate, composition of, 184. 

Sohngen, 45. 

Soil, absorbent power of, 27, 31 ; 
as an absorbent of ammonia, 30. 

Soil disinfection, good effects of, 
endure long, 365 ; may not be 
generally applicable, 365. 

Solid solution, definition of, 250. 

Soluble phosphoric acid, see phos- 
phoric acid, soluble. 

Solution, solid, see solid solution. 

Sombrero phosphate, 185. 

Somme phosphates, 181. 

Soot, benefits soils physically, 108 
chemical composition of, 108 
light, is best, 108 ; nature of, 107 
often rich in ammonia, 107 
rarely toxic, 108. 

South Carolina phosphates, 182. 

Spent tan, absorbent power of, 
27. 

Spruce, Norway, manganese in, 
354. 

Stable manure, see manure. 

Stahl-Schroeder, 346. 

Star-fish, composition of, 92, 93. 

Stauf, 147. 

Stead, 195. 

Stockhardt, 289, 318. 

Stohmann, 6, 344. 

Stoklasa, 35, 41. 

Storer, 92, 243, 267, 271, 288, 310, 
319, 337. 



Strasburger, 36 ; Noll, Schenck, and 
Shimper, 317. 

Stutzer, 150, 318. 

Sulfate of ammonia, see ammonium 
sulfate. , 

Sulfate of potash, see potassium 
sulfate. 

Sulfate of potash, high grade, 240 ; 
low grade, 237, 240. 

Sulfate of potash and magnesia, 
237. 

Sulfur, amount of, in hay and 
legumes, 358 ; carried in the rain- 
fall, 359 ; essential to plant 
growth, 357 ; important in essen- 
tial oils, 357 ; in cress, 357 ; in 
certain German potash salts, 

357 ; in gypsum, 357 ; in horse- 
radish, 357 ; in proteins, 357 ; in 
superphosphate, 357 ; losses of, 
by leaching at Rothamsted, 359 ; 
may perhaps become depleted in 
soils, 358 ; relation of, to phos- 
phorus in the plant and soil, 358 ; 
amounts of, removed by cabbages, 

358 ; removed from soils in large 
amounts by some crops, 358 ; re- 
moved to the extent of 40 per 
cent from soils long cropped, 358 ; 
returned to soils in farm-yard 
manures, 358 ; should be further 
investigated, 359 ; supposed to be 
seldom if ever deficient in soils, 
357. 

Sulfuric acid, as a preservative of 
manure, 34. 

Sullivan, see Schreiner. 

Superphosphate, aids maturity and 
starch production in potatoes, 
227 ; as a preservative of manure,. 
33 ; best adapted to what crops, 
226, 227 ; care in the manufac- 
ture of, 203, 204 ; double, cheap 
to transport, 205; double, 37, 
204, 205, 206 ; double, manufac- 
ture of, 205 ; especially adapted 
to the top-dressing of grass and 
grain, 226 ; especially helpful, 
with other ingredients, for sugar 



388 



INDEX 



beets, 227 ; fixation chiefly in 
surface soil, 222 ; fixation of, in 
soils rapid, 221, 222; flocculat- 
ing action of, 225 ; free phos- 
phoric acid in, 202 ; injury from, 
rare, 223 ; made from various sub- 
stances, 201 ; manufacture begun 
by Lawes in the year 1842, 7; 
may give inferior results on cer- 
tain soils, 225 ; preparation of, 
201, 202, 204. 

Superphosphatgyps, 37. 

Sutherst, 355. 

Suzuki, 345. 

Sylvanit, 236, 237 ; composition of, 
237, 239. 

Tacke, 243. 

Takeuchi, 331. . 

Tangle, 65, 66, 67, 230. 

Tankage, availability of nitrogen 

in, 122. 
Tankage, bone, as a fertilizer, 96 ; 

composition of, 96, 172 ; method 

of employment of, 96 ; nature of, 

95 ; value of nitrogen of, 96. 
Tannery hair, composition of, 103. 
Tennant, 319. 
Tennessee phosphate, 184. 
Teuthorn, 17. 
Thaer, 3. 

Thaxter, 299, 301. 
Thiel, C, 104. 
Thielavia basicola, 297. 
Thiocyanates as an impurity in 

ammonium sulfate, 147. 
Thomas and Gilchrist, 191. 
Thomas meal, see basic slag meal. 
Thomas phosphate, see basic slag 

meal. 
Thomas phosphate powder, see 

basic slag meal. 
Thon, 17. 
Thurneyssen, 87. 
Tobacco, best lime-magnesia ratio 

for, 332. 
Tobacco stems, potash in, 232. 
Toluene, 40 ; effect of, on soils, 

363. 



Toluene treatment of soils, de- 
stroys protozoa, 364 ; increases 
ammonification, 364; results of, 
364. 

Treadwell and Reuter, 327. 

Tricalcium phosphate, see phos- 
phate. 

Tricresol, 40 ; effect of, on soils, 363. 

Tull, Jethro, 2. 

Turgor, effect of potassium on, 255. 

Ullao, 75. 

Ullmann, 247. 

Urea, 29, 163 ; decomposition of, 
in manure, 44, 45, 46. 

Uric acid, decomposition of, in 
manure, 47 ; in guano, 76. 

Urine, amount of, produced per per- 
son, 11 ; human, chemical com- 
position of, 11, 12; microorgan- 
isms essentially absent from, 36 ; 
nitrification of, aided by calcium 
sulfate, 285. 

Urobacillus duclauxii, 46. 

Urobacillus jakschii, 46. 

Urobacillus pasteuri, 45. 

Van Senus, 43. 

Vauquelin and Klaproth, 165 ; see 

Fourcroy. 
Vega, Garcilaso de la, 75. 
Viard, 211. 
Vibrans, 230, 231. 
Ville, 4, 317, 319. 
Virgil, 1. 

Vivianite, an iron phosphate, 188. 
Voelcker, 139, 152, 158, 159, 251, 

355. 
Von Feilitzen, H., 200, 243. 
Von Freudenreich, 35. 
Von Raumer, E., .316, 319. 
Von Wagner, L., 246, 323. 
Von Wolff, E., 316. 
Voorhees, 92, 100, 120. 

Wachsmann, 345. 

Wagner, 95, 120, 140, 157, 362; 

and Dorsch, 116; 119, 143, 150, 

152, 157, 346. 



INDEX 



389 



Wagnerite, 178. 
Warrington, 131, 313, 362. 
Water-slaked lime, see hydrated 

lime. 
Wavellite, an iron phosphate, 185. 
Waxes and fats, decomposition of, 

in manure, 44. 
Way, 250. 

Weiser and Zaitschek, 41. 
Western phosphates, 184. 
Whale, fat difficult to separate, 90 ; 

glue sometimes used as a ferti- 
lizer, 90 ; guano, 90. 
Whale-bone, composition of, 90. 
Whale waste, 88 ; composition of, 89. 
Wheat, best lime-magnesia ratio 

for, 331 ; effect of manganese on, 

355. 
Wheat straw, absorbent power of, 

27, 31. 
Wheeler and Hartwell, 4, 67, 105, 

119, 230, 231, 232, 247, 256, 260, 

324, 329, 336; Hartwell and 

Pember, 349. 
Whitney, M., 362. 
Wiborgh phosphate, constitution 

of, 198; now superseded by 

Palmaer phosphate, 199. 



Wilfarth, 4, 105, 260, 347; see 
Hellriegel. 

Wolff, 336, 360. 

Wolter's phosphate, process of 
manufacture of, 199 ; solubility 
of, in citric acid, 199. 

Wood ashes, composition of, 228. 

Wool, composition of, 103. 

Wool, waste, as a manure, 104 ; 
composition of, 104 ; effect of 
superheated steam on, 104 ; 
Petermann's test of availabil- 
ity of, possible errors in, 105 ; 
soluble, not lost by leaching, 
105. 

Worms and slugs, action of lime on, 
267, 268. 

Wurtz, 243. 

Wiitrich and Von Freudenreich, 
35. 

Wyoming, phosphates of, 184. 

Yeasts in manure, 39. 

Zaitschek, see Weiser. 

Zoller, 336. 

Zostera marina, 65, 69, 231. 



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